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We present an analysis of hot and dilute isospin-asymmetric nuclear matter employing the temperature-dependent effective-relativistic mean-field theory (E-RMF). We consider nuclear matter to be homogeneous and study the equation of state (EoS) for densities, temperature, and asymmetry which are relevant for astrophysical simulations such as supernovae explosion and neutron-star crust. The two recently developed E-RMF parameter sets IOPB-I and G3 are used here to study various physical observables at finite temperatures. These sets are known to reproduce the nuclear matter properties, in agreement with various experimental and observational constraints. The effect of temperature is investigated in reference to the density-dependent free symmetry energy and its higher-order derivatives using the well-known parabolic approximation. The larger value of ${\ensuremath{\lambda}}_{\ensuremath{\omega}}$ cross coupling in G3 in addition to the $\ensuremath{\delta}$ meson coupling in G3 smoothen the free symmetry energy. Thermal effects on various state variables are examined at fixed temperature and isospin asymmetry by separating their $T=0$ and the finite-$T$ expressions. The thermal effects are governed by effective mass where larger effective mass corresponds to larger thermal contribution. The effect of temperature on isothermal and isentropic incompressibility is discussed, which is in harmony with various microscopic calculations. The liquid-gas phase-transition properties are examined in asymmetric matter in the context of different slope parameter and comparable symmetry energy in the IOPB-I and G3 set. The spinodal instability, binodal curve, and critical properties are found to be influenced by the slope parameter ${L}_{\mathrm{sym}}$. Finally, we consider a more realistic system (with the inclusion of electrons) and analyze the effect on instability and adiabatic index of isospin asymmetric nuclear matter.

This research paper offers a simple and original approach to extend the resonant frequency tuning range from high-to-low frequencies in electrostatically actuated microelectromechanical systems (MEMS) based resonators. Typically, it is possible to achieve low frequencies in MEMS through increasing the effective mass or decreasing the mechanical stiffness in micro structures. However, this work intends, assuming a double-sided electrodes design, to control the excited mode of the micro-system in order achieve low frequencies through DC bias voltage variations and possibly eliminating the displacement dependency in capacitive micro-bridges-based structures. The design consists of a flexible microbeam where its equations of motion are derived within the framework of the nonlinear Euler–Bernoulli beam theory. The equations are then solved using the reduced-order modeling based on the Galerkin modal decomposition and while considering the couple-stress theory. Simulations show an improved performance of the micro- structure as compared to previous investigations. In addition, a wider frequency tuning range has been achieved through a proper DC bias voltage arrangement.

Imaging the vibrations of nanomechanical resonators means measuring their flexural mode shapes from the dependence of their frequency response on in-plane position. Applied to two-dimensional resonators, this technique provides a wealth of information on the mechanical properties of atomically-thin membranes. We present a simple and robust system to image the vibrations of few layer graphene (FLG) resonators at room temperature and in vacuum with an in-plane displacement precision of ≈0.20 μm. It consists of a sturdy vacuum enclosure mounted on a three-axis micropositioning stage and designed for free space optical measurements of vibrations. The system is equipped with ultraflexible radio frequency transmission lines to electrically actuate resonators. With it we characterize the lowest frequency mode of FLG resonators by measuring its frequency response as a function of position on the membrane and by extracting its effective mass. We use the background noise of the undriven vibrational spectrum to calibrate in-plane displacement. Finally, we measure the first three vibration modes of a resonator whose membrane is partially folded and find that folds locally suppress vibrations.

Charge transport in amorphous silicon nitride (Si3N4) is studied experimentally in a wide range of electric fields and temperatures. The experimental data are compared with the results of numerical calculations. To describe the ionization of deep centers (traps) in Si3N4, the Frenkel effect is used with the account for thermally assisted tunneling and the multiphonon mechanism. It is shown that the Frenkel effect with allowance for thermally assisted tunneling formally describes the experiment. However, an anomalously small frequency factor (109 s–1) and a large effective tunneling mass (3m0) must be used in calculations in this case. A satisfactory agreement between the results of experiments and calculations was attained using the theory of multiphonon ionization of traps with the following parameters: $$W_{T}^{{e,h}}$$ = 1.6 eV, $$W_{{{\text{opt}}}}^{{e,h}}$$ = 3.2 eV, $$W_{{{\text{ph}}}}^{{e,h}}$$ = 0.064 eV, $$m_{{e,h}}^{*}$$ = 0.6m0, and Ne,h = 6 × 1018 cm–3, which correspond to the thermal energy, optical energy, phonon energy, tunneling effective mass, and concentrations of electron and hole traps, respectively.

This study aims to develop a multiscale method that will help improve drug delivery systems. A finite volume heterogeneous multiscale method (FV-HMM) is propounded to model mass transport by considering cell scale heterogeneity in the biological tissues. The partition phenomenon is included in the mass transport model. A new upscaling technique has been devised to evaluate the effective mass transport at the macro level. An interface method based on alternating direction implicit scheme is used to solve the microscale models. FV-HMM is used to study the tissue penetration efficacy of drug nanoparticles. Numerical experiments are performed with different parameters, and it is concluded that partition phenomenon and particle size are the important factors on tissue penetration efficacy of nanoparticles in drug delivery. Also, FV-HMM is used to determine the biological cell geometry impact on drug penetration at the tissue scale.

The substitutional semiconductor obtained by doping $${\text{In}}_{2} {\text{O}}_{3}$$ with aluminum metal has potential applications in high-quality gas sensors and nanoelectronic devices. The structural and electrooptical properties of new $$\left( {{\text{In}}_{1 - x} {\text{Al}}_{x} } \right)_{2} {\text{O}}_{3}$$ alloys with compositions corresponding to x = 0, 0.25, 0.75, and 1 are theoretically calculated herein by using density functional theory (DFT). The exchange correlation functional is treated with the Perdew–Burke–Ernzerhof (PBE) generalized gradient approximation (GGA) to study the effect of the composition on the structural parameters of $$\left( {{\text{In}}_{1 - x} {\text{Al}}_{x} } \right)_{2} {\text{O}}_{3}$$ . Additional treatment with the accurate Tran–Blaha modified Becke–Johnson (TB-mBJ) scheme is applied to improve the electronic band structure and optical constants of the compositions. The influence of alloying with Al on the structural parameters, energy bandgap, and electron effective mass is investigated. The direct bandgap of the $$\left( {{\text{In}}_{1 - x} {\text{Al}}_{x} } \right)_{2} {\text{O}}_{3}$$ alloys increases with increasing Al percentage in the studied compositions. In addition, the influence of pressure on the lattice parameters is also studied. Their linear optical parameters are evaluated in the range of 0–40 eV. The optical results show an improvement in the optical transparency of the studied alloys in the infrared and visible ranges as the Al content $$x$$ is increased. This suggests that such new $$\left( {{\text{In}}_{1 - x} {\text{Al}}_{x} } \right)_{2} {\text{O}}_{3}$$ ternary alloys could be promising candidate transparent materials for use in optoelectronic applications.

High electron mobility transistors built using $$\hbox {In}_{0.52}\hbox {Al}_{0.48}\hbox {As}$$ / $$\hbox {In}_{0.53}\hbox {Ga}_{0.47}\hbox {As}$$ on InP substrates are currently being investigated for numerous applications due to their favorable performance for microwave, optical and digital applications. We present a detailed and comprehensive study of steady-state and transient electronic transport in $$\hbox {In}_{0.52}\hbox {Al}_{0.48}\hbox {As}$$ with a three-valley model using the semi-classical ensemble Monte Carlo method including all important scattering mechanisms. Electronic transport parameters such as drift velocity, valley occupation, average electron energy, ionization coefficient and generation rate, electron effective mass, diffusion coefficient, energy and momentum relaxation time are extracted rigorously from the simulations. Using these, we present a detailed characterization of the transient electronic transport showing the variation of drift velocity with distance and time. We further estimate the optimal cut-off frequencies for various device lengths via the velocity overshoot effect. Our analysis shows that transient effects are significant for device lengths shorter than 700 nm and should be taken into account for optimal device designs. As a critical example at length scales of around 100 nm, we obtain a significant improvement in the cut-off frequency from 261 GHz to 663 GHz with the inclusion of transient effects. The field dependence of all extracted parameters done here can prove to be highly useful for further device analysis and design.

Using the active feedback control system on the elastic wave metamaterial, this research concentrates on the sound transmission with the dynamic effective model. The metamaterial is subjected to an incident pressure and immersed in the external mean flow. The elastic wave metamaterial consists of double plates and the upper and lower four-link mechanisms are attached inside. The vertical resonator is attached by the active feedback control system and connected with two four-link mechanisms. Based on the dynamic equivalent method, the metamaterial is equivalent as a single-layer plate by the dynamic effective parameter. With the coupling between the fluid and structure, the expression of the sound transmission loss (STL) is derived. This research shows the influence of effective mass density on sound transmission properties, and the STL in both modes can be tuned by the acceleration and displacement feedback constants. In addition, the dynamic response and the STL are also changed obviously by different values of structural damping, incident angle (i.e., the elevation and azimuth angles) and Mach number of the external fluid with the mean flow property. The results for sound transmission by two methods are compared, i.e., the virtual work principle for double plates and the dynamic equivalent method corresponding to a single one. This paper is expected to be helpful for understanding the sound transmission properties of both pure single- and double-plate models.

An analytical model is presented to study metaelastic dynamic behaviors of rigid sphere-reinforced elastic random composites. The model is based on the concept that the deviation of the displacement field of embedded rigid spheres from the displacement field of the composite is responsible for novel metaelastic dynamic behaviors of stiff sphere-reinforced composites. Compared to the existing models, the present model offers a simple general method to analyze various 3D metaelastic dynamic problems of rigid sphere-reinforced random composites, and its validity and efficiency are demonstrated by comparing the predicted results with known experimental or numerical data on several typical steel/glass/lead-polymer composites. Several basic dynamic problems of rigid sphere-reinforced composite beams and rods are investigated, and some metaelastic dynamic phenomena (such as vibration isolation, localized buckling, and natural frequency within the bandgap caused by an attached concentrated mass) of stiff sphere-reinforced composites are demonstrated.

Reverse gate-leakage of the AlGaN/GaN heterostructure field-effect transistors (HFETs) is studied at different values of drain–source voltage ( ${V}_{\text {DS}}$ ), ranging from 0 to 10 V. Throughout the investigated range of ${V}_{\text {DS}}$ , the reported analysis confirms the applicability of the Fowler–Nordheim (FN) tunneling as the dominant contributor to the gate-leakage for reverse gate biases until the onset of the threshold voltage. Device simulations were performed using Comsol Multiphysics to estimate the electric field ( $E\,\,$ ) across the polar III-nitride barrier layer at different positions along the gate length. We observe that the FN tunneling takes place predominantly corresponding to the average electric field observed to be close to ${E} $ at the center of the gate for lower values of ${V}_{\text {DS}}$ , whereas at larger values of ${V}_{\text {DS}}$ , FN tunneling corresponding to ${E}$ only at the drain edge of the gate seems poised to deliver the gate-leakage current. In formulating the FN tunneling, the value of the electron effective mass is selected consistently within an acceptable range for analyzing gate-leakage. Investigating the applicability of FN tunneling in explaining the reverse gate-leakage current of AlGaN/GaN HFETs for the aforementioned values of gate to source voltage ( ${V}_{\text {GS}}$ ) not just at zero ${V}_{\text {DS}}$ , but across a range of ${V}_{\text {DS}}$ values, seems to offer a more convincing argument for the hypothesis on tunneling through small leakage zones.

Two-dimensional (2D) materials with anisotropic electronic structures possess promising prospect for ultra-scaled field effect transistors (FETs), such as black phosphorene. Here, the quantum transport properties of anisotropic 2D group VA-VA monolayers with puckered configuration are studied in 5 nm FETs using density functional theory and nonequilibrium Green’s function. Through evaluating and comparing the transport effective mass ( $\text{m}_{x}$ ) and density of state ( $\text{m}_{\text {DOS}}$ ) of these 2D group VA-VA monolayers, we uncover the physical mechanism of the anisotropic electronic structures for the performances of 2D ultra-short FETs. These electronic structures can make the channel with a small $\text{m}_{x}$ hold a high $\text{m}_{\text {DOS}}$ , or the channel with heavy $\text{m}_{x}$ hold a small $\text{m}_{\text {DOS}}$ , which is beneficial to obtain high saturation current, steep sub-threshold swing, and thus a high on-current. Hence, the strong anisotropic electronic structure can be regarded as a target feature for designing high performance 2D FETs, which provides a guideline for exploring excellent 2D channels for ultra-scaled electronic devices.

We calculate the nucleon parameters – the effective mass $$m{\text{*}}$$ , vector self energy $${{\Sigma }_{V}}$$ and the binding energy per nucleon $$\mathfrak{P}$$ in terms of QCD condensates. We study the equilibrium states of the matter. We employ the QCD sum rules approach. Including the condensates with d = 6 we find equilibrium states of nuclear matter for $${{{\sigma }}_{N}} > 41$$ MeV. The equilibrium is due to influence of the relativistic motion of nucleons on the scalar quark condensate.

In this study, we develop an analytical formula to approximate the damping coefficient as a function of the coefficient of restitution for a class of continuous contact models. The contact force is generated by a logical point-to-point force element consisting of a linear damper connected in parallel to a spring with Hertz force–penetration characteristic, while the exponent of deformation of the Hertz spring can vary between one and two. In this nonlinear model, it is assumed that the bodies start to separate when the contact force becomes zero. After separation, either the restitution continues or a permanent penetration is achieved. Therefore, this model is capable of addressing a wide range of impact problems. Herein, we apply an optimization strategy on the solution of the equations governing the dynamics of the penetration, ensuring that the desired restitution is reproduced at the time of separation. Furthermore, based on the results of the optimization process along with analytical investigations, the resulting optimal damping coefficient is analytically expressed at the time of impact in terms of system properties such as the effective mass, penetration velocity just before the impact, coefficient of restitution, and the characteristics of the Hertz spring model.

In this paper an analytical stability criterion for linear haptic devices is determined, in the presence of the operator. The model of the haptic device and the virtual environment are assumed as mass-damper and spring-damper, respectively. Two different models for operator’s hand are assumed, and the stability boundaries are derived analytically. The main contribution of this paper is the analytical formulation of a closed-form stability equation in the presence of the operator; which can predict the stability boundary with small and even large values of virtual damping and time delay. This closed-form stability criterion can be useful in applications such as haptic rendering of deformable objects using finite element method, where the computational time delay is considerable. The influence of operator’s hand and effective mass on the stability is studied analytically and verified by simulations and experiments on a KUKA Light Weight Robot.

The results of calculation of the three-loop radiative correction to the renormalization constant of fermion masses for non-abelian gauge theory interacting with fermions are presented. Dimensional regularization and the 't Hooft minimal subtraction scheme are used. The method of calculation is described in detail. The renormalization group function $\gamma_m$ determining the behavior of the effective mass of fermions is presented. The anomalous dimensions of fermions for QED and QCD up to three loops are given. All calculations were performed on a computer with the help of the SCHOOONSCHIP system for analytical manipulations. The present text was published in 1982 as a JINR Communication, JINR-P2-82-900 (in russian)., Comment: 11 pages

Within the effective mass and the parabolic band approximations, the binding energy of an on-center shallow donor impurity in a $$\mathrm{GaAs}/{\mathrm{Ga}}_{1-x}{\mathrm{Al}}_{x}\mathrm{As}$$ multilayered spherical quantum dot has been studied by using the Finite Element Method (FEM). The ground state energy is calculated as a function of the barrier width and inner dot radius for different values of the confinement potential height. Our numerical results exhibit that the binding energy depends strongly on the width of the structure layers. In addition, we have investigated the effect of pressure, temperature, and electric field on the shallow donor binding energy. The calculations showed that the pressure yielded a significant improvement in the binding energy, especially for small inner dot radii. We have also remarked that the presence of temperature leads to a decrease in the binding energy, and the electric field produces a significant effect on the binding energy except for small barrier widths, where the coupling effect between the dots is the most dominant.

We report a comprehensive magnetization and magnetotransport study on a metallic-type of ${\mathrm{EuMnSb}}_{2}$ single crystals. A large Hall signal up to room temperature is found in our metallic ${\mathrm{EuMnSb}}_{2}$, which is dominated by hole carriers with very low carrier density and high mobility. Clear Shubnikov--de Haas oscillations are observed at low temperatures (T $l$ 30 K), from which a dominant tiny hole pocket with small effective mass is deduced. The interplay of carrier density and Mn and Eu moments results in complex magnetic ground states with two successive antiferromagnetic (AFM) transitions appearing at ${T}_{N1}=24 \mathrm{K}$ and ${T}_{N2}=9 \mathrm{K}$. In line with the rich magnetic phases, the transport properties, including magnetoresistance, quantum oscillation, and Berry phase, experience abrupt disturbances when crossing the magnetic phase boundaries. The Dirac state is likely quenched once the AFM orders set in, indicating a strong coupling between the AFM magnetic order and the band topology. Our results suggest that metallic-type ${\mathrm{EuMnSb}}_{2}$ is an ideal platform for the study of the interplay between magnetism, charge transport, and band topology.

In the current 3ν paradigm, neutrino flavor oscillations probe three mixing angles (θ12,θ23,θ13), one CP-violating phase δ, and two independent differences between the squared masses mi2, that can be chosen as δm2=m22−m12>0 and Δm2=m32−(m12+m22)/2, where sign(Δm2)=+(−) for normal (inverted) mass ordering. Absolute ν masses can be probed by the effective mass mβ in beta decay, by the total mass Σ in cosmology and—if neutrinos are Majorana—by another effective mass mββ in neutrinoless double beta decay. Within an updated global analysis of oscillation and nonoscillation data, we constrain these 3ν parameters, both separately and in selected pairs, and highlight the concordance or discordance among different constraints. Five oscillation parameters (δm2,|Δm2|,θ12,θ23,θ13) are consistently measured, with an overall accuracy ranging from ∼1% for |Δm2| to ∼6% for sin2θ23 (due to its persisting octant ambiguity). We find overall hints for normal ordering (at ∼2.5σ), as well as for θ23<π/4 and for sinδ<0 (both at 90% C.L.), and discuss some tensions among different datasets. Concerning nonoscillation data, we include the recent KATRIN constraints on mβ, and we combine the latest Ge76, Te130 and Xe136 bounds on mββ, accounting for nuclear matrix element covariances. We also discuss some variants related to cosmic microwave background (CMB) anisotropy and lensing data, which may affect cosmological constraints on Σ and hints on sign(Δm2). The default option, including all Planck results, irrespective of the so-called lensing anomaly, sets upper bounds on Σ at the level of ∼10−1 eV, and further favors normal ordering up to ∼3σ. An alternative option, that includes recent ACT results plus other independent results (from WMAP and selected Planck data) globally consistent with standard lensing, is insensitive to the ordering but prefers Σ∼few×10−1 eV, with different implications for mβ and mββ searches. In general, the unfinished fabric of the 3ν paradigm appears to be at the junction of diverse searches in particle and nuclear physics, astrophysics and cosmology, whose convergence will be crucial to achieve a convincing completion.

Isoscalar and isovector effective masses of the nucleon in nuclear medium are explored in the quasi-elastic electron scattering of nuclei with KIDS (Korea-IBS-Daegu-SKKU) density functional model. Effective masses are varied in the range (0.7 ~ 1.0)$M$ where $M$ is the mass of the nucleon in free space. Parameters in the KIDS functional are adjusted to nuclear matter equation of state, energy and radius of selected nuclei, and effective mass of nucleons. Hartree-Fock equation is solved to obtain the wave functions of the nucleon in target nuclei, and they are plugged in the calculation of electron-nucleus scattering cross sections at the energies of incident electrons 300 MeV ~ 2.5 GeV. Theoretical prediction agrees well with measurement. Dependence on the effective mass is evident: cross section tends to increase with small isoscalar effective masses. However, effect of isovector effective mass is negligible. Spectroscopic factors are estimated for the protons in the outermost shells of $^{16}$O, $^{40}$Ca, and $^{208}$Pb. Results are consistent with the values in the literature., Comment: 20 pages, 9 figures

Interfacial electron-phonon coupling in ultrathin films has attracted much interest recently. Here, by combining angle-resolved photoemission spectroscopy and scanning tunneling microscopy, we report quantized electronic states and strong interfacial electron-phonon coupling in ultrathin Yb films on graphite. We observed clear kinks in the energy-momentum dispersion of quantum well states, and the kink positions agree well with the energies of optical phonons of graphite. The extracted coupling strength $\ensuremath{\lambda}$ is largest for the thinnest film with a preferred (``magic'') thickness of four monolayers and exhibits a strong band dependence, which can be qualitatively accounted for by a simple model. The interfacial electron-phonon coupling also gives rise to characteristic steplike structures in the $dI/dV$ spectra, implying dominant coupling with the phonons with zero in-plane momentum. A Lifshitz transition occurs at higher coverage, where quantum well states derived mainly from $5d$ electrons dominate near the Fermi level and possess large effective mass (up to $\ensuremath{\sim}19\phantom{\rule{0.28em}{0ex}}{m}_{e}$). Our results highlight the potentially important role of interfacial electron-phonon interaction for ultrathin films and provide spectroscopic insight to understand this cross-interface fermion-boson interaction.

The Shockley surface state located at $\overline{\mathrm{Y}}$ on the $(1\ifmmode\times\else\texttimes\fi{}2)$-reconstructed Au(110) surface is predicted to exhibit a Rashba-type spin splitting. Previous photoemission experiments searched for this splitting but it could not be resolved yet. In order to uncover a possible splitting, the unoccupied surface state on Au(110) is examined with spin- and angle-resolved inverse photoemission, whereas Na-covered Au(110) allows for investigation of the now occupied surface state by means of spin- and angle-resolved direct photoemission. Our data show clear spin splittings in the order of $100\phantom{\rule{0.16em}{0ex}}\mathrm{meV}$ with a sign reversal at $\overline{\mathrm{Y}}$ in the surface state's in-plane spin components which is characteristic for a Rashba-type behavior. Furthermore, we deduce an effective mass of ${m}^{*}=(0.27\ifmmode\pm\else\textpm\fi{}0.02){m}_{e}$ and a Rashba parameter of ${\ensuremath{\alpha}}_{R}=(0.46\ifmmode\pm\else\textpm\fi{}0.04)\phantom{\rule{0.16em}{0ex}}\mathrm{eV}\phantom{\rule{0.16em}{0ex}}\AA{}$ from direct photoemission measurements.

The electric structure of twisted bilayer GeSe, which shows a rectangular moir\'{e} pattern, is analyzed using a $\bm{k}\cdot\bm{p}$ type effective continuum model. The effective model is constructed on the basis of the the local approximation method, where the local lattice structure of a twisted bilayer system is approximated by its untwisted bilayer with parallel displacement, and the required parameters are fixed with the help of the first-principles method. By inspecting the twist angle dependence of the physical properties, we reveal a relation between the effective potential under moir\'{e} pattern and the alignment of the Ge atoms, and also the resultant one-dimensional flat band, where the band is flattened stronger in a specific direction than the perpendicular direction. Due to the relatively large effective mass of the original monolayers, the flat band with its band width as small as a few meV appear in a relatively large angle. This gives us an opportunity to explore the dimensional crossover in the twisted bilayer platform., Comment: 11 pages, 6 figures

Topological fermions have mainly been addressed in the limit of weakly correlated systems, while the realization of Kondo-like physics arising from Dirac-Weyl fermions and implying strong correlations is rare. The noncentrosymmetric Weyl fermion $R\mathrm{AlGe}$ compounds (with $R=\mathrm{La} \mathrm{and} \mathrm{Ce}$) provide a promising playground for revealing the impact of electronic correlations driven by $f$-electron states on Weyl fermions. Here, we tackle their charge dynamics as a function of temperature. Besides spotting typical optical signatures of a type-II Weyl semimetal in both materials, we discover that electronic correlations at low temperatures renormalize the nontrivial bands hosting the Weyl nodes and lead to a reduction of the Fermi velocity as well as an enhancement of the charge carriers effective mass in CeAlGe with respect to LaAlGe, both being a fingerprint of a so-called Weyl-Kondo system.

Transition metal doped ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ with high mobility can be used as a transparent conductor with enhanced transparency spectral window. In this work, we carried out a comprehensive study on the electrical and optical properties of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$ doped with several transition metal (TM) species (${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$) including W, Zr, Mo, and Ti. Detailed optical properties obtained by spectroscopic ellipsometry (SE) are correlated with electrical properties obtained by Hall effect measurements. We find that the mobility of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$ thin films lies in the range of $50\text{--}75\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\text{\ensuremath{-}}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\text{\ensuremath{-}}1}$, much higher than the typical mobility of $30\text{--}40\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\text{\ensuremath{-}}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\text{\ensuremath{-}}1}$ for conventional ITO. The complex dielectric functions of the thin films reveal remarkable carrier density dependent changes in the optical properties. SE analyses show that the electron effective mass of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$ at the bottom of the conduction band ${m}_{o}^{*}$ ($0.11\text{--}0.14{m}_{o}$) is much smaller than the reported ${m}_{o}^{*}\ensuremath{\sim}0.18\ensuremath{-}0.30{m}_{o}$ for ITO, which directly results in their higher mobility. This low ${m}_{o}^{*}$ is consistent with recent theoretical studies which proposed that $4d$ donor states of the TMs are resonance in the CB. For films with comparably low resistivity of $1\text{--}2\ifmmode\times\else\texttimes\fi{}{10}^{\text{\ensuremath{-}}4}\phantom{\rule{0.16em}{0ex}}\mathrm{\ensuremath{\Omega}}\phantom{\rule{0.16em}{0ex}}\mathrm{cm}$, we find that ${\mathrm{In}}_{2}{\mathrm{O}}_{3}:\mathrm{TM}$ films have \ensuremath{\sim}4--10 times lower absorption coefficient at $\ensuremath{\lambda}=1300\phantom{\rule{0.16em}{0ex}}\mathrm{nm}$ due to free carrier absorption and have their plasma reflection edge extended to \ensuremath{\sim}1.7 \ensuremath{\mu}m compared to \ensuremath{\sim}1.2--1.4 \ensuremath{\mu}m for ITO. Hence, using TM doping we have achieved transparent conductors with conductivity comparable to ITO but with transmission extended to g1600 nm. These materials will be potentially important as transparent conductors for optoelectronic devices utilizing NIR photons.

This study investigated the electronic structure of $\mathrm{Sr}{\mathrm{Ti}}_{1\text{\ensuremath{-}}x}{\mathrm{V}}_{x}{\mathrm{O}}_{3}$ (STVO) thin films, which are solid solutions of strongly correlated transparent conductive oxide (TCO) $\mathrm{SrV}{\mathrm{O}}_{3}$ and oxide semiconductor $\mathrm{SrTi}{\mathrm{O}}_{3}$, using in situ photoemission spectroscopy. STVO is one of the most promising candidates for correlated-metal TCO because it has the capability of optimizing the performance of transparent electrodes by varying $x$. Systematic and significant spectral changes were found near the Fermi level (${E}_{\mathrm{F}}$) as a function of $x$, while the overall electronic structure of STVO is in good agreement with the prediction of band-structure calculations. As $x$ decreases from 1.0, spectral weight transfer occurs from the coherent band near ${E}_{\mathrm{F}}$ to the incoherent states (lower Hubbard band) around 1.0--1.5 eV. Simultaneously, a pseudogap is formed at ${E}_{\mathrm{F}}$, indicating a significant reduction in quasiparticle spectral weight within close vicinity of ${E}_{\mathrm{F}}$. This pseudogap seems to evolve into an energy gap at $x=0.4$, suggesting the occurrence of a composition-driven metal-insulator transition. From angle-resolved photoemission spectroscopic results, the carrier concentration $n$ changes proportionally as a function of $x$ in the metallic range of $x=0.6--1.0$. In contrast, the mass enhancement factor, which is proportional to the effective mass (${m}^{*}$), does not change significantly with varying $x$. These results suggest that the key factor of $n/{m}^{*}$ in optimizing the performance of correlated-metal TCO is tuned by $x$, highlighting the potential of STVO to achieve the desired TCO performance in the metallic region.

Investigating Shubnikov-de Haas (SdH) oscillations in high magnetic fields, we experimentally infer the electronic band structure of the quasi-two-dimensional electron gas (2DEG) at the ionic-liquid gated amorphous ($a$)-${\mathrm{LaAlO}}_{3}/{\mathrm{KTaO}}_{3}$ interface. The angular dependence of SdH oscillations indicates a 2D confinement of a majority of electrons at the interface. However, additional SdH oscillations with an angle-independent frequency observed at high tilt angles indicate the coexistence of 3D charge carriers extending deep into the ${\mathrm{KTaO}}_{3}$. The SdH oscillations measured in magnetic fields perpendicular to the interface show four frequencies corresponding to four 2D subbands with different effective masses ($0.20\phantom{\rule{0.16em}{0ex}}{m}_{e}\ensuremath{-}0.55\phantom{\rule{0.16em}{0ex}}{m}_{e}$). The single-frequency oscillations originating from 3D electrons yields a larger effective mass of $\ensuremath{\sim}0.70\phantom{\rule{0.16em}{0ex}}{m}_{e}$. Overall, the inferred subbands are in good agreement with the theoretical calculations and angle-resolved photoemission spectroscopy studies on 2DEG at ${\mathrm{KTaO}}_{3}$ surface.

We developed a theory of electric and thermoelectric conductivity of lightly doped SrTiO$_3$ in the non-degenerate region $k_B T \geq E_F$, assuming that the major source of electron scattering is their interaction with soft transverse optical phonons present due to proximity to ferroelectric transition. We have used kinetic equation approach within relaxation-time approximation and we have determined energy-dependent transport relaxation time $\tau(E)$ by the iterative procedure. Using electron effective mass $m$ and electron-transverse phonon coupling constant $\lambda$ as two fitting parameters, we are able to describe quantitatively a large set of the measured temperature dependences of resistivity $R(T)$ and Seebeck coefficient $\mathcal{S}(T)$ for a broad range of electron densities studied experimentally in recent paper [1]. In addition, we calculated Nernst ratio $\nu=N/B$ in the linear approximation over weak magnetic field in the same temperature range., Comment: 10 pages, 7 figures

Owing to its strong ionic character coupled with a light electron effective mass, $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ is an unusual semiconductor where large electric fields (approximately 1--6 MV/cm) can be applied while still maintaining a dominant excitonic absorption peak below its ultrawide band gap (${E}_{g}$ \ensuremath{\sim} 4.6--4.99 eV). This provides a rare opportunity in the solid state to examine exciton and carrier self-trapping dynamics in the strong-field limit at steady state. Under sub-band-gap photon excitation, we observe a field-induced redshift of the spectral photocurrent peak associated with exciton absorption and a thresholdlike increase in peak amplitude at high field associated with self-trapped hole ionization. The field-dependent spectral response is quantitatively fitted with an exciton-modified Franz-Keldysh effect model, which includes the electric-field-dependent exciton-binding energy due to the quadratic Stark effect. Saturation of the spectral redshift with reverse bias is observed exactly at the onset of dielectric breakdown, providing a spectral means to detect and quantify the local electric field and dielectric breakdown behavior in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$. Additionally, the field-dependent responsivity provides an insight into the photocurrent-production pathway, revealing the photocurrent contributions of self-trapped excitons (STXs) and self-trapped holes (STHs) in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$. Photocurrent and p-type transport in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ are quantitatively explained by field-dependent tunnel ionization of excitons and self-trapped holes. We employ a quantum-mechanical model of the field-dependent tunnel ionization of STXs and STHs in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ to model the nonlinear field dependence of the photocurrent amplitude. Fitting to the data, we estimate an effective mass of valence-band holes (18.8${m}_{0}$) and an ultrafast self-trapping time of holes (0.045 fs). This indicates that minority-hole transport in $\ensuremath{\beta}\text{\ensuremath{-}}{\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ can only arise through tunnel ionization of STHs under strong fields.

We revisit the localized Wannier state description of the twisted bilayer graphene, focusing on the chiral limit. We provide a simple method for constructing such 2D exponentially localized -- yet valley polarized -- Wannier states, centered on the sites of the honeycomb lattice, paying particular attention to maintaining all the unobstructed symmetries. This includes the unitary particle-hole symmetry, and the combination of $C_2\mathcal{T}$ and the chiral particle-hole symmetry. The $C_2\mathcal{T}$ symmetry alone remains topologically obstructed and is not represented in a simple site-to-site fashion. We also analyze the gap and the dispersion of single particle and single hole excitations above a strong coupling ground state at integer fillings, which we find to be dominated by the on-site and the nearest neighbor terms of a triangular lattice hopping model, with a minimum at the center of the moire Brillouin zone. Finally, we use the insight gained from this real space description to understand the dependence of the gap and the effective mass on the range of the screened Coulomb interaction., Comment: 19 pages; (14p main text + 1.2p references + 4p supplementary) 7 figures

This paper presents a vibration-based electromagnetic energy harvester whose resonance frequency can be adjusted to match that of the excitation. Frequency adjustment is attained by controlling a rotatable arm, with tuning masses, at the tip of a cantilever-type energy harvester, thereby changing the effective mass moment of inertia of the system. The rotatable arm is mounted on a servomotor that is autonomously controlled through a microcontroller and a photo sensor to keep the device at resonance for maximum power generation. A mathematical model is developed to predict the system response for different design parameters and to estimate the generated power. The system is investigated analytically by a distributed-parameter model to study the natural frequency variation and dynamic response. The analytical model is verified experimentally where the frequency is tuned from 8 to 10.25 Hz. A parametric study is performed to study the effect of each parameter on the system behavior.

The paper is devoted to the dynamics of a zero thickness infinite vortex filament in the local induction approximation. The filament is asymptotically considered as a straight line defined by the certain vector ${\boldsymbol{b}}_3 \in E_3$. We also investigate the possibility of interpretation of such object as a planar “quaziparticle”. The configuration space for some “collective coordinates” for such object is the plane $E_2 \perp {\boldsymbol{b}}_3$. The “quaziparticle” has a certain number of the internal degrees of the freedom. The Hamiltonian description of the filament is constructed in terms of the variables allowing the natural classification into “external” and “internal” groups. The external variables (coordinates and momenta of a planar structureless particle) and the internal ones (the variables for the continuous Heisenberg spin chain) are entangled by the constraints. Because of these constraints, the constructed theory is non-trivial. The space symmetry group of the system was constructed by two stages: the contraction $ SO(3) \to E(2)$ and the subsequent extension $E(2) \times T \to \tilde{\mathcal G}_2$. The group $E(2)$ is the group of the plane motion for the plane $E_2 \perp {\boldsymbol{b}}_3$, symbol $T$ denotes the group of time translations and the group $\tilde{\mathcal G}_2$ is the central extended Galilei group for the plane mentioned above. The appearance of the Galilei group makes it possible to introduce the invariant Cazimir functions for the Lee algebras for this group and to formulate the new approach for the problem of the energy of the infinite vortex filament with zero thickness. The formula for the tensor of the inverse effective mass of the constructed system is also being deduced. It is demonstrated that the suggested theory can be interpreted as a model of the planar vortex particle having an infinite number of internal degrees of freedom.

Particle damping is a promising damping technique for a variety of technical applications. However, their non-linear behavior and multitude of influence parameters, hinder currently its wide practical use. So far, most researchers focus either on determining the energy dissipation inside the damper or on the overall damping behavior when coupled to a structure. Indeed, currently almost no knowledge exchange between both approaches occurs. Here, a bridge is build to combine both techniques for systems under forced vibrations by coupling the energy dissipation field and effective particle mass field of a particle damper with a reduced model of a vibrating structure. Thus, the overall damping of the structure is estimated very quickly. This combination of both techniques is essential for an overall efficient dimensioning process and also provides a deeper understanding of the dynamical processes. The accuracy of the proposed coupling method is demonstrated via a simple application example. Hereby, the energy dissipation and effective mass of the particle damper are analyzed for a large excitation range first using a shaker setup. The particle damper exhibits multiple areas of different efficiency. The underlying structure is modeled using FEM and modal reduction techniques. By coupling both parts it is shown that multiple eigenmodes of the structure are highly damped using the particle damper. The damping prediction using the developed coupling procedure is validated via experiments of the overall structure with particle damper.

It was observed recently [Shigekawa et al., PNAS 116, 2470 (2019)] that while monolayer iron chalcigenide FeSe on a ${\text{SrTiO}}_{3}$ (STO) substrate has a very high critical temperature, its chemical and structural twin material FeS/STO has a very low ${T}_{c}$, if any. To explain this, the substrate interfacial phonon model of superconductivity in iron chalcogenides is further developed. The main glue is the oxygen ion ${\mathrm{\ensuremath{\Omega}}}_{s}=60\phantom{\rule{0.16em}{0ex}}\text{meV}$ vibrations longitudinal optical (LO) mode. The mode propagates mainly in the ${\text{TiO}}_{2}$ layer adjacent to the monolayer (and also generally present in similar highly polarized ionic crystals like ${\text{BaTiO}}_{3},$ rutile, and anatase). It has stronger electron-phonon coupling to electron gas in FeSe than a well-known ${\mathrm{\ensuremath{\Omega}}}_{h}=100\phantom{\rule{0.16em}{0ex}}\text{meV}$ harder LO mode. It is shown that while (taking into account screened Coulomb repulsion effects) the critical temperature of FeSe on STO and ${\text{TiO}}_{2}$ is above $65\phantom{\rule{0.16em}{0ex}}\text{K}$, it becomes less than $5\phantom{\rule{0.16em}{0ex}}\text{K}$ for FeS due to two factors suppressing the electron-phonon coupling. The effective mass in the latter is twice smaller and, in addition, the distance between the electron gas in FeSe to the vibrating substrate oxygen atoms is 15% smaller than in FeS, reducing the central peak in electron-phonon interaction. The theory is extended to other ionic insulating substrates.

We report a systematic study of the superconducting (SC) and normal-state anisotropy of ${\mathrm{Fe}}_{1+y}{\mathrm{Te}}_{0.6}{\mathrm{Se}}_{0.4}$ single crystals with controlled amounts of excess Fe ($y$ = 0, 0.07, and 0.14). The SC state anisotropy ${\ensuremath{\gamma}}_{H}$ was obtained by measuring the upper critical fields under high magnetic fields over 50 T for both $H\ensuremath{\parallel}ab$ and $H\ensuremath{\parallel}c$. On the other hand, the normal state anisotropy ${\ensuremath{\gamma}}_{\ensuremath{\rho}}$ was obtained by measuring the resistivity with current flowing in the $ab$ plane (${\ensuremath{\rho}}_{ab}$) and along the $c$ axis (${\ensuremath{\rho}}_{c}$). To precisely measure ${\ensuremath{\rho}}_{ab}$ and ${\ensuremath{\rho}}_{c}$ in the same part of a specimen avoiding the variation dependent on pieces or parts, we adopt a new method using a microfabricated bridge with an additional neck part along the $c$ axis. The ${\ensuremath{\gamma}}_{H}$ decreases from a value dependent on the amount of excess Fe at ${T}_{\mathrm{c}}$ to a common value $\ensuremath{\sim}1$ at 2 K. The different ${\ensuremath{\gamma}}_{H}$ at ${T}_{\mathrm{c}}$ ($\ensuremath{\sim}1.5$ for $y$ = 0, and 2.5 for $y$ = 0.14) suggests that the anisotropy of effective mass ${m}_{c}^{*}/{m}_{ab}^{*}$ increases from $\ensuremath{\sim}2.25$ ($y$ = 0) to 6.25 ($y$ = 0.14) with the excess Fe. The almost isotropic ${\ensuremath{\gamma}}_{H}$ at low temperatures is due to the strong spin paramagnetic effect at $H\ensuremath{\parallel}ab$. By contrast, the ${\ensuremath{\gamma}}_{\ensuremath{\rho}}$ shows a much larger value of $\ensuremath{\sim}17$ ($y$ = 0) to $\ensuremath{\sim}50$ ($y$ = 0.14) at the temperature just above ${T}_{\mathrm{c}}$. Combined the results of ${\ensuremath{\gamma}}_{H}$ and ${\ensuremath{\gamma}}_{\ensuremath{\rho}}$ near ${T}_{\mathrm{c}}$, we found out that the discrepant anisotropies between the SC and normal states originates from a large anisotropy of scattering time ${\ensuremath{\tau}}_{ab}/{\ensuremath{\tau}}_{c}\phantom{\rule{4pt}{0ex}}\ensuremath{\sim}$ 7.8. The ${\ensuremath{\tau}}_{ab}/{\ensuremath{\tau}}_{c}$ is found to be independent of the excess Fe.

By means of high-pressure resistivity measurements on single crystals, we investigate the charge transport properties of ${\mathrm{Cu}}_{x}{\mathrm{PdTe}}_{2}$, notable for the combination of topological type-II Dirac semimetallic properties with superconductivity up to ${T}_{c}=2.5\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. In both pristine $(x=0)$ and intercalated $(x=0.05)$ samples, we find an unconventional ${T}^{4}$ power law behavior of the low-temperature resistivity visible up to $\ensuremath{\sim}40$ K and remarkably stable under pressure up to 8.2 GPa. This observation is explained by the low carrier density $n$, which strongly reduces the $k$ region available for electron-phonon scattering, as previously reported in other low-$n$ two-dimensional systems, such as multilayer graphene and semiconductor heterostructures. Our data analysis complemented by specific heat measurements and supported by previous quantum oscillation studies and ab initio calculations suggests a scenario of one-band charge transport. Within this scenario, our analysis yields a large value of the transport electron-phonon coupling constant ${\ensuremath{\lambda}}_{tr}=1.2$ at ambient pressure that appears to be strongly enhanced by pressure assuming a constant effective mass.

We address theoretically the problem of laser-induced dynamics of an electron, whose effective mass is position dependent (e.g., due to an effect of a semiconductor nanostructure environment). We derive the associated classical acceleration-gauge Hamiltonian ${H}_{\mathrm{AG}}(t)$ under the most general conditions, even without imposing the dipole approximation. It is shown that ${H}_{\mathrm{AG}}(t)$ possesses an intriguing structure arising due to the spatial dependence of the electronic mass. Subsequently, we restrict ourselves to a weak-field intensity regime, and derive the corresponding quantum mechanical acceleration-gauge Hamiltonian ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{H}}_{\mathrm{AG}}(t)$ which differs from its classical counterpart by an extra quantum term, $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathrm{QM}}$. Our theoretical findings are illustrated numerically by calculating the probability ${|T(E)|}^{2}$ of the resonance transmission of an electron through a model semiconductor nanostructure. It is demonstrated that the quantum mechanical $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{\mathrm{QM}}$ term of ${\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{H}}_{\mathrm{AG}}(t)$ does often affect crucially the profile of ${|T(E)|}^{2}$.

Analysis of bipolar thermal conductivity might be very useful in preliminary stages of thermoelectric materials discovery. Using its product---mobility ratio between electrons and holes---it is possible to choose the most promising compound from the series and pave the correct direction of doping. Current work presents positive verification of this approach for $\mathrm{Sc}\mathrm{Ni}\mathrm{Sb}$, which is anticipated to show superior mobility when tuned towards n-type behavior. In agreement with expectation, the mobility increases by an order of magnitude due to rising tellurium content in the ${\mathrm{Sc}\mathrm{Ni}\mathrm{Sb}}_{1\ensuremath{-}x}{\mathrm{Te}}_{x}$ series. The effect is most likely driven by change of the dominant charge carriers' scattering mechanism from ionized impurity influence to point defect and acoustic phonon interaction. Simultaneously, due to a highly anisotropic conduction band, the effective mass of the carriers rises towards the n-type regime. These two effects lead to an improved thermoelectric power factor of electron-doped samples, up to $40\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}{\mathrm{WK}}^{\ensuremath{-}2}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ at 740 K for ${\mathrm{Sc}\mathrm{Ni}\mathrm{Sb}}_{0.85}{\mathrm{Te}}_{0.15}$. Based on this result, we suggest n-type doping for other rare-earth-based half-Heusler compounds. Representatives of this group exhibit the smallest lattice thermal conductivity in the pristine form among any half-Heusler thermoelectrics, and are anticipated to show comparably good electrical properties to ScNiSb due to their high mobility ratio in favor of electrons.

The nuclear matrix element (NME) of the neutrinoless double-$\beta$ ($0\nu\beta\beta$) decay is an essential input for determining the neutrino effective mass, if the half-life of this decay is measured. The reliable calculation of this NME has been a long-standing problem because of the diversity of the predicted values of the NME depending on the calculation method. In this paper, we focus on the shell model and the QRPA. The shell model have a rich amount of the many-particle many-hole correlations, and the QRPA can obtain the convergence of the result of calculation with respect to the extension of the single-particle space. It is difficult for the shell model to obtain the convergence of the $0\nu\beta\beta$ NME with respect to the valence single-particle space. The many-body correlations of the QRPA are insufficient depending on nuclei. We propose a new method to modify phenomenologically the results of the shell model and the QRPA compensating the insufficient point of each method by using the information of other method complementarily. Extrapolations of the components of the $0\nu\beta\beta$ NME of the shell model are made toward a very large valence single-particle space. We introduce a modification factor to the components of the $0\nu\beta\beta$ NME of the QRPA. Our modification method gives similar values of the $0\nu\beta\beta$ NME of the two methods for $^{48}$Ca. The NME of the two-neutrino double-$\beta$ decay is also modified in a similar but simpler manner, and the consistency of the two methods is improved., Comment: 21 pages, 4 figures, section VII was modified

Binary neutron star mergers provide a unique probe of the dense-matter equation of state (EoS) across a wide range of parameter space, from the zero-temperature EoS during the inspiral to the high-temperature EoS following the merger. In this paper, we implement a new model for calculating parametrized finite-temperature EoS effects into numerical relativity simulations. This ``${M}^{*}$-model'' is based on a two-parameter approximation of the particle effective mass and includes the leading-order effects of degeneracy in the thermal pressure and energy. We test our numerical implementation by performing evolutions of rotating single stars with zero- and nonzero temperature gradients, as well as evolutions of binary neutron star mergers. We find that our new finite-temperature EoS implementation can support stable stars over many dynamical timescales. We also perform a first parameter study to explore the role of the ${M}^{*}$ parameters in binary neutron star merger simulations. All simulations start from identical initial data with identical cold EoSs, and differ only in the thermal part of the EoS. We find that both the thermal profile of the remnant and the postmerger gravitational wave signal depend on the choice of ${M}^{*}$ parameters, but that the total merger ejecta depends only weakly on the finite-temperature part of the EoS across a wide range of parameters. Our simulations provide a first step toward understanding how the finite-temperature properties of dense matter may affect future observations of binary neutron star mergers.

We study the general embedding of a $P(X,\ensuremath{\varphi})$ inflationary theory into a two-field theory with a curved field space metric, which was proposed as a possible way to examine the relation between de Sitter swampland conjecture and $k$-inflation. We show that this embedding method fits into the special type of two-field model in which the heavy field can be integrated out at the full action level. However, this embedding is not exact due to the upper bound of the effective mass of the heavy field. We quantify the deviation between the speed of sound calculated via the $P(X,\ensuremath{\varphi})$ theory and the embedded two-field picture to next leading order terms. We especially focus on the first potential slow-roll parameter defined in the two-field picture and obtain an upper bound on it.

An exact treatment of the operators $Q/e(\ensuremath{\omega})$ and the total momentum is adopted to solve the nuclear matter Bruecker-Bethe-Goldstone equation with two- and three-body forces. The single-particle potential, equation of state, and nucleon effective mass are calculated from the exact $G$ matrix. The results are compared with those obtained under the angle-average approximation and the angle-average approximation with total momentum approximation. It is found that the angle-average procedure, whereas preventing huge calculations of coupled channels, nevertheless provides a fairly accurate approximation. On the contrary, the total momentum approximation turns out to be quite inaccurate compared to its exact counterpart.

Collision experiments in the human-robot interaction (HRI) context showed that the effective robot mass is one of the main parameters that influence human injury probability during a collision. Also the current standard ISO/TS 15066 highlights the importance of this parameter and provides a method to determine the maximum safe robot velocity based on the effective mass. To enable both safe and efficient robot applications, it is crucial to derive the robot's instantaneous effective mass sufficiently accurate based on either a), a kinematic and dynamic model or b), a suitable collision experiment. In this paper, we describe and quantitatively compare the well-established reflected mass model by Khatib and the simplified model provided in the ISO/TS 15066 for the KUKA LWR IV + and the Franka Emika Panda robot. Furthermore, we propose a method to practically determine the effective mass using a passive mechanical pendulum setup. Our results show that the simplified ISO/TS model can lead to a significant safety-relevant error. With our preliminary experimental setup, however, we can verify that the reflected mass obtained by the dynamics model only differs 1.1-7.8 % from the measured value.

We report a comprehensive study of the electronic structure of layered compound $\mathrm{Ba}\mathrm{Cd}{\mathrm{Sb}}_{2}$ by using electrical transport measurements, first-principles calculations, and angle-resolved photoemission spectroscopy (ARPES). The samples show semiconductorlike temperature dependence of resistivity and low carrier density. The Shubnikov-de Haas (SdH) oscillations with a single frequency reveal a small two-dimensional (2D) cylinderlike Fermi surface (FS), a light cyclotron effective mass, and trivial Berry's phase. Quantum limit can be achieved under a moderate magnetic field. The calculated bands without any renormalization are well consistent with the ARPES results, showing the Dirac band crossing with 2D character near the Fermi energy and a gap of about 34 meV at the Dirac point induced by spin-orbit interaction. The SdH oscillations can be identified to the Dirac band by the similar cross sectional areas of FSs. Our findings indicate $\mathrm{Ba}\mathrm{Cd}{\mathrm{Sb}}_{2}$ is a promising material for researching the quantum phenomena of the 2D Dirac fermions.

We combine transport, angle-resolved photoemission spectroscopy, and scanning tunneling spectroscopy to investigate several low-energy manifestations of the Hund's coupling in a canonical FeSC family Li(Fe,Co)As. We determine the doping dependence of the coherent-incoherent crossover temperature and the quasiparticle effective mass enhancement in the normal state. Our tunneling spectroscopy result in the superconducting state supports the idea that superconductivity emerging from Hund's metal state displays a universal maximal superconducting gap vs transition temperature ($2{\mathrm{\ensuremath{\Delta}}}_{\mathrm{max}}/{k}_{B}{T}_{c}$) value, which is independent of doping level and ${T}_{c}$.

International audience; We present an analytical model to account for the deformation-induced inertial dynamics of a magnetic vortex. The model is based on a deformation of the vortex core profile based on the Döring kinetic field, whereby the deformation amplitudes are promoted to dynamical variables in a collective-coordinate approach that provides a natural extension to the Thiele model. This extended model describes complex transients due to inertial effects and the variation of the effective mass with velocity. The model also provides a quantitative description of the inertial dynamics leading up to vortex core reversal, which is analogous to the Walker transition in domain wall dynamics. Our work paves the way for a standard prescription for describing the inertial effects of topological magnetic solitons.

We report on results of first-principles electronic structure calculations on disordered $\mathrm{Zn}(\mathrm{Si},\mathrm{Ge},\mathrm{Sn}){\mathrm{N}}_{2}$ alloys. These calculations on substitutional disordered alloys are carried out using the Korringa-Kohn-Rostoker Green function (KKR-GF) method in combination with the coherent potential approximation (CPA) alloy theory. The band gaps and effective masses as well as the disorder-induced finite lifetime of electronic states at the conduction band minimum and valence band maximum are evaluated by analyzing the Bloch spectral functions. Relativistic effects are found to have a small impact and in particular the influence of the spin-orbit coupling is negligible. The alloys with low Si content show band gaps and effective masses which change almost linearly with the composition. Their relatively small effective mass and long lifetime indicate a high charge carrier mobility.

Devising the two-dimensional (2D) structures of low-cost and non-toxic semiconductors for nanoscale technological applications has attracted substantial interest since the past decade. In this work, we design two types of ZnO monolayers derived from polar 0001-plane and nonpolar $$11\overline{2}0$$ -plane of the wurtzite structure, and explore their physical properties using the first-principles approach. Both ZnO $$\left( {11\overline{2}0} \right)$$ and ZnO(0001) monolayers exhibited cohesive and formation energies comparable to that of the stable wurtzite-structured ZnO. However, both monolayers exhibited substantially different electronic structures of band gaps 1.56 eV for single-layered ZnO $$\left( {11\overline{2}0} \right)$$ and 0.71 eV for ZnO(0001) monolayer. The edges of the valence and conduction bands of ZnO $$\left( {11\overline{2}0} \right)$$ monolayer are formed by parabolic bands, whereas almost flat band gap edges have been seen for ZnO(0001) surface. As a result, charge carriers associated with ZnO $$\left( {11\overline{2}0} \right)$$ monolayer exhibited relatively lighter effective mass than ZnO(0001) monolayer. The ZnO(0001) monolayer exhibited symmetrical bond lengths and subsequently isotropic optical spectra, whereas asymmetrical bond lengths and anisotropic subsequent optical spectra have been recorded for ZnO $$\left( {11\overline{2}0} \right)$$ monolayer. The optical absorption recorded for the designed monolayers has been found higher than their bulk counterpart. The refraction spectra indicated these monolayers of transparent behavior over a significant range of the electromagnetic spectrum. These fascinating features of ZnO $$\left( {11\overline{2}0} \right)$$ and ZnO(0001) monolayers suggest them suitable for applications in electronic and optoelectronic devices.

Monolayer (ML) transition metal dichalcogenides (TMDCs) emerged as ideal materials to combine spin and momentum of charge carriers for spintronics and valleytronics applications. Despite its relevance for TMDC-based technology, the impact of the various many-body-like interactions of charge carriers with defects, phonons, and other system's quasiparticles on the charge dynamics and transport properties remains experimentally elusive, being commonly overshadowed by the strong ML interactions with other materials (such as substrate and contacts) introduced in standard experimental approaches. Here, a method combining interface engineering and angle-resolved photoemission spectroscopy (ARPES) enables a direct investigation of the impact of many-body effects on the hole quasiparticle dynamics of ${\mathrm{WS}}_{2}$ ML on graphite and extraction of relevant transport parameters. In particular, at the valence band edge, a clear ARPES line-shape asymmetry is observed, mainly reflecting the hole interaction with intralayer electrons and defects while a negligible hole-phonon coupling is found. Using the valley hole quasiparticle lifetime and effective mass extracted from ARPES data at different temperatures, we estimated a hole mobility of $\ensuremath{\sim}300\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{2}\phantom{\rule{0.16em}{0ex}}{\mathrm{V}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, comparable to some of the highest values reported by transport measurements.

We study the properties of a spin-down neutron impurity immersed in a low-density free Fermi gas of spin-up neutrons. In particular, we analyze its energy ($E_\downarrow$), effective mass ($m^*_\downarrow$) and quasiparticle residue ($Z_\downarrow$). Results are compared with those of state-of-the-art quantum Monte Carlo calculations of the attractive Fermi polaron realized in ultracold atomic gases experiments, and with those of previous studies of the neutron polaron. Calculations are performed within the Brueckner--Hartree--Fock approach using the chiral two-body nucleon-nucleon interaction of Entem and Machleidt at N$^3$LO with a 500 MeV cut-off and the Argonne V18 phenomenological potential. Only contributions from the $^1S_0$ partial wave, which is the dominant one in the low-density region considered, are included. Contributions from three-nucleon forces are expected to be irrelevant at these densities and, therefore, are neglected in the calculation. Our results show that for Fermi momenta between $\sim 0.25$ and $\sim 0.45$ fm$^{-1}$ the energy, effective mass and quasiparticle residue of the impurity vary only slightly, respectively, in the ranges $-0.604\,E_F < E_\downarrow < -0.635\,E_F $, $1.300\,m < m^*_\downarrow < 1.085\, m$ and $0.741, Comment: 6 pages, 2 figures. Accepted for publication as a Letter in Physical Review C

Cosmic birefringence is predicted if an axion-like particle (ALP) moves after the recombination. We show that this naturally happens if the ALP is coupled to the dark matter density because it then acquires a large effective mass after the matter-radiation equality. Our scenario applies to a broad range of the ALP mass $m_\phi \lesssim 10^{-28}$ eV, even smaller than the present Hubble constant. We give a simple model to realize this scenario, where dark matter is made of hidden monopoles, which give the ALP such a large effective mass through the Witten effect. The mechanism works if the ALP decay constant is of order the GUT scale without a fine-tuning of the initial misalignment angle. For smaller decay constant, the hidden monopole can be a fraction of dark matter. We also study the implications for the QCD axion, and show that the domain wall problem can be solved by the effective mass., Comment: 6 pages, 2 figures