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The influence of Rashba spin-orbit interaction on the transport properties of the two-dimensional quantum ring with finite width has been investigated in the presence of the uniform perpendicular magnetic field. The dependence of magnetoresistance on the magnetic field and Rashba spin-orbit coupling parameter in quantum ring with finite width are investigated. It was shown that in the presence Rashba spin-orbit interaction that the beating pattern is destroyed.

Transition metal dichalcogenide (TMD) semiconductors are attracting much attention in research regarding device physics based on their unique properties that can be utilized in spintronics and valleytronics. Although current studies concentrate on the monolayer form due to the explicitly broken inversion symmetry and the direct band gap, bulk materials also hold the capability of carrying spin and valley current. In this study, we report the methodology to continuously control the spin-orbit coupling (SOC) strength of bulk TMDs Mo1-xWxSe2 by changing the atomic ratio between Mo and W. The results show the size of band splitting at the K valley the measure of the coupling strength is linearly proportional to the atomic ratio of Mo and W. Our results thus demonstrate how to precisely tune the SOC coupling strength, and the collected information of which can serve as a reference for future applications of bulk TMDs.

A theoretical investigation of the structural, electronic, magnetic, and magneto-elastic properties is provided for the non-perovskite HoMnO3 in low symmetry. This study has been carried out using density functional theory (DFT + U) with the inclusion of the polarized spin and spin-orbit coupling for both ferromagnetic and antiferromagnetic configurations. The generalized gradient approximation (GGA), the GGA + U, and modified Becke-Johnson (mBJ) approach have been used. The stability of the ground state of this compound in ferromagnetic (FM) and antiferromagnetic (AFM) configurations has been highlighted, confirming the magnetic behavior of HoMnO3. A good agreement has been observed between the internal atomic relaxation calculations and the experimental data. The calculated total magnetic moment of HoMnO3, localized on Ho atom is about ~ 9.6 µB for the ferromagnetic configuration, in good agreement with the available experimental data. On other hand, the GGA and GGA + U (where U ~ 7 eV) approximations have predicted a metallic behavior behavior for the h-HoMnO3, whereas, the implementation of mBJ approach has highlighted a semiconductor feature of the HoMnO3 with spin-polarized band gap about 0.5 eV (FM) and 0.6 eV (AFM). The calculated Bulk modulus has been found to be about 162.23 GPa (FM), and 169.34 GPa (AFM).

Current-induced magnetization switching by spin-orbit torque generated in heavy metals offers an enticing realm for energy-efficient memory and logic devices. The spin Hall efficiency is a key parameter in describing the generation of spin current. Recent findings have reported enhancement of spin Hall efficiency by mechanical strain, but its origin remains elusive. Here, we demonstrate a 45% increase in spin Hall efficiency in the platinum/cobalt (Pt/Co) bilayer, of which 78% of the enhancement was preserved even after the strain was removed. Spin transparency and X-ray magnetic circular dichroism revealed that the enhancement was attributed to a bulk effect in the Pt layer. This was further confirmed by the linear relationship between the spin Hall efficiency and resistivity, which indicates an increase in skew-scattering. These findings shed light on the origin of enhancement and are promising in shaping future utilization of mechanical strain for energy-efficient devices. Agency for Science, Technology and Research (A*STAR) Economic Development Board (EDB) National Research Foundation (NRF) Submitted/Accepted version This work is supported by an Industry-IHL Partnership Program (NRF2015-IIP001-001) and an EDB-IPP (RCA − 17/284) grant. This work is also supported by the RIE2020 ASTAR AME IAF-ICP grant (No. I1801E0030). W.Z. and P.K.J.W. acknowledge financial support by the Fundamental Research Funds for the Central Universities.

Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron-electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron-electron interactions can modify this coupling. Here we demonstrate the emergence of SOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system features also strong electron-electron interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron-electron interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regime and to the formation of novel quasiparticles with the electron spin strongly coupled to the density., Main Text (4 Figures), Supplementary notes (4 Figures)

The structural, electronic and thermodynamic properties of LaRuX (X = Si, Ge) compounds are investigated using density functional theory by the Wien2k code. Using the first-principles procedure, the Hubbard parameter of La 5d electrons and Ru 4d electrons of LaRuX (X = Si, Ge) compounds is calculated. In these calculations, the exchange–correlation potential is calculated using the generalized gradient approximation (GGA) and generalized gradient approximation plus Hubbard parameter (GGA + U). The calculated results indicate that LaRuX (X = Si, Ge) compounds are stable in the nonmagnetic phase. The electron density of states and band structure of LaRuX (X = Si, Ge) compounds within GGA and GGA + U approaches in the presence of spin orbit coupling are calculated. The obtained results of the electronic band structure show that LaRuX (X = Si, Ge) compounds have metallic behavior. Furthermore, thermodynamic properties of LaRuX (X = Si, Ge) compounds using the quasi-harmonic Debye model within GGA and GGA + U approaches are investigated.

The Berry phase, which reveals the intimate geometrical structure underlying quantum mechanics, plays a central role in the anomalous Hall effect. In this work, we observed a sign change of Berry curvatures at the interface between the ferromagnet SrRuO3 (SRO) layer and the SrIrO3 (SIO) layer with strong spin-orbit coupling. The negative Berry curvature at the interface, induced by the strongly spin-orbit-coupled Ir 5d bands near the Fermi level, makes the SRO/SIO interface different from the SRO layer that has a positive Berry curvature. These opposite Berry curvatures led to two anomalous Hall effect (AHE) channels with opposite signs at the SRO/SIO interface and in the SRO layer, respectively, resulting in a hump-like feature in the Hall resistivity loop. This observation offers a straightforward explanation of the hump-like feature that is usually associated with the chiral magnetic structure or magnetic skyrmions. Hence, this study provides evidence to oppose the widely accepted claim that magnetic skyrmions induce the hump-like feature.

Through a combination of density functional theory calculations and cluster-expansion formalism, the effect of the configuration of the transition metal atoms and spin-orbit coupling on the thermodynamic stability and electronic bandgap of monolayer 2H-Mo1-xWxS2 is investigated. Our investigation reveals that, in spite of exhibiting a weak ordering tendency of Mo and W atoms at 0 K, monolayer 2H-Mo1-xWxS2 is thermodynamically stable as a single-phase random solid solution across the entire composition range at temperatures higher than 45 K. The spin-orbit coupling effect, induced mainly by W atoms, is found to have a minimal impact on the mixing thermodynamics of Mo and W atoms in monolayer 2H-Mo1-xWxS2; however, it significantly induces change in the electronic bandgap of the monolayer solid solution. We find that the band-gap energies of ordered and disordered solid solutions of monolayer 2H-Mo1-xWxS2 do not follow Vegard's law. In addition, the degree of the SOC-induced change in band-gap energy of monolayer 2H-Mo1-xWxS2 solid solutions not only depends on the Mo and W contents, but for a given alloy composition it is also affected by the configuration of the Mo and W atoms. This poses a challenge of fine-tuning the bandgap of monolayer 2H-Mo1-xWxS2 in practice just by varying the contents of Mo and W.

Here, we used collinear and noncollinear density functional theory (DFT) methods to explore the interfacial properties of two heterojunctions between a fullerene (C60 and C70) and the MAPbI3(110) surface. Methodologically, consideration of the spin-orbit interaction has been proven to be required to obtain accurate energy-level alignment and interfacial carrier dynamics between fullerenes and perovskites in hybrid perovskite solar cells including heavy atoms (such as Pb atoms). Both heterojunctions are predicted to be the same type-II heterojunction, but the interfacial electron transfer process from MAPbI3 to C60 is completely distinct from that to C70. In the former, the interfacial electron transfer is slow because of the associated large energy gap, and the excited electrons are thus trapped in MAPbI3 for a while. In contrast, in the latter, the smaller energy gap induces ultrafast electron transfer from MAPbI3 to C70. These points are further supported by DFT-based nonadiabatic dynamics simulations including the spin-orbit coupling (SOC) effects. These gained insights could help rationally design superior fullerene-perovskite interfaces to achieve high power conversion efficiencies of fullerene-perovskite solar cells.

The electronic structure and spectroscopic properties of the germanium dimer have been investigated by high-level ab initio calculations with consideration of spin-orbit coupling (SOC). The potential energy curves (PECs) of 19 Λ-S states, as well as those of 52 Ω states generated from the Λ-S states, are calculated by the multireference configuration interaction plus Davidson correction (MRCI + Q) method. The properties of the F3Σ+u1-X3Σ-g1 and H3Σ-u1-X3Σ-g1 transitions as well as the interactions of the F3Σ+u and H3Σ-u states with other excited states induced by SOC are investigated based on the calculated SO matrix and the PECs of the Ω states. Our results indicate that the previously observed spectra of Ge2 in the range 20 500-22 000 cm-1 should be assigned as the transition between the Ω = 1g component of the X3Σ-g state and Ω = 1u of the F3Σ+u state. Moreover, owing to the strong SOC with the repulsive 25Πu state, the H3Σ-u state is predissociative, leading to the Ge(3P2) + Ge(3P1) channel at vibrational levels higher than v' = 6. Our theoretical study would provide comprehensive information and shed light on understanding the spectroscopy and dynamics of the electronic excited states of Ge2.

Spin-orbit coupling (SOC), the relativistic effect describing the interaction between the orbital and spin degrees of freedom, provides an effective way to tailor the spin/magnetic orders using electrical means. Here, we report the manipulation of the spin-orbit interaction in the lattice-matched InSb/CdTe heterostructures. Owing to the energy band bending at the heterointerface, the strong Rashba effect is introduced to drive the spin precession where pronounced weak antilocalization cusps are observed up to 100 K. With effective quantum confinement and suppressed bulk conduction, the SOC strength is found to be enhanced by 75% in the ultrathin InSb/CdTe film. Most importantly, we realize the electric-field control of the interfacial Rashba effect using a field-effect transistor structure and demonstrate the gate-tuning capability which is 1-2 orders of magnitude higher than other materials. The adoption of the InSb/CdTe integration strategy may set up a general framework for the design of strongly spin-orbit coupled systems that are essential for CMOS-compatible low-power spintronics.

Two dimensional (2D) materials are currently gaining a lot of interest due to excellent properties that are different from their bulk structures. Single and few-layered of Transition metal dichalcogenides (TMDCs) have a bandgap that ranges between 1-2 eV, which is used for FET devices or any optoelectronic devices. Within TMDCs, a ton of consideration is focused on Molybdenum Disulfide (MoS2) because of its promising band gap-tuning and transition between direct to indirect bandgap properties relies upon its thickness. The density functional theory (DFT) calculations with different functionals and spin-orbit coupling (SOC) parameters were carried out to study the electronic properties of bulk and monolayer MoS2. The addition of SOC brought about a noteworthy change in the profile of the band energy, explicitly the splitting of the valence band maximum (VBM) into two sub-bands. The indirect bandgap in bulk MoS2 ranges from 1.17- 1.71eV and that of the monolayer bandgap was 1.6 – 1.71eV. The calculated parameters were compared to the obtained experimental and theoretical results. The obtained density of states (DOS) can be used in explaining the nature of bandgap in both the bulk and monolayer MoS2. These electronic characteristics are important for applications in material devices and energy-saving applications

We investigate the crossed Andreev reflection (CAR) through a quantum dot (QD) coupled to topological superconducting single-stranded DNA (ssDNA). It is found that the topological nontrivial states appear in the QD due to leakage of the Majorana zero mode. Majorana zero mode can be identified by measuring the CAR. This device can be used as a Majorana zero mode detector that relies on the system parameters, such as the spin orbit coupling, the twist angle, molecular length. A high efficiency Cooper pair splitter can be realized by regulating the magnitude and direction of the gate voltage. In additions, the signature of CAR is robust against the Coulomb blockade and the disorder induced by distinct amino acids. This work provides an alternative method for detection of Majorana zero mode in ssDNA.

A theoretical investigation of the combined resonance of interlayer conductivity and spin magnetization, in conductors with quasi-two-dimensional electronic energy spectra. Analytical expressions are obtained for the surface impedance, magnetic susceptibility, and the resonance interlayer conductivity component caused by Rashba–Dresselhaus spin-orbit interaction, with allowance for spatial dispersion.

Made available in DSpace on 2021-06-25T10:34:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Indian Institute of Technology Ropar Department of Science and Technology, Government of Kerala After the pioneering studies on spinor Bose-Einstein condensate (BEC) and after the realization of spin-orbit (SO) coupling in a spinor BEC of 87Rb and 23Na atoms, it is now realized that an SO-coupled BEC may reveal new physical phenomena not possible in a scalar BEC. For example, a new class of two- or three-dimensional vector soliton can be stabilized and observed in an SO-coupled BEC, whereas such a soliton is unstable in a scalar BEC. In this paper, we present a review on solitons in an SO-coupled spin-1 spinor BEC in one, two, and three space dimensions. In addition to the static properties of these solitons, we also consider their dynamics of motion with a constant velocity and collision between two solitons. Department of Physics Indian Institute of Technology Ropar Instituto de Física Teórica UNESP - Universidade Estadual Paulista, 01.140-070 São Paulo Instituto de Física Teórica UNESP - Universidade Estadual Paulista, 01.140-070 São Paulo CNPq: 301324/2019-0 Indian Institute of Technology Ropar: 9-256/2016/IITRPR/823 Department of Science and Technology, Government of Kerala: ECR/2017/001436

Reverse intersystem crossing (RISC), the uphill spin-flip process from a triplet to a singlet excited state, plays a key role in a wide range of photochemical applications. Understanding and predicting the kinetics of such processes in vastly different molecular structures would facilitate the rational material design. Here, we demonstrate a theoretical expression that successfully reproduces experimental RISC rate constants ranging over five orders of magnitude in twenty different molecules. We show that the spin flip occurs across the singlet–triplet crossing seam involving a higher-lying triplet excited state where the semi-classical Marcus parabola is no longer valid. The present model explains the counterintuitive substitution effects of bromine on the RISC rate constants of previously unknown molecules, providing a predictive tool for material design., Understanding and predicting the kinetics of reverse intersystem crossing (RISC) facilitates the design of materials. Here, the authors demonstrate a theoretical expression that reproduces experimental RISC rate constants ranging over five orders of magnitude in selected molecules.

Based on the effective mass approximation, the magnetic and thermal properties of parabolic GaAs quantum dot have been investigated in the presence of Rashba Spin-Orbit interaction (RSOI), donor impurity and applied magnetic and electric fields. The exact diagonalization method has been used to solve the Hamiltonian of an electron confined in a quantum dot (QD) and obtain the eigenenergies and the binding energy of the donor impurity as a function of various QD physical parameters. We have shown the dependence of the average statistical energy, magnetization, magnetic susceptibility and heat capacity of the donor impurity in the QD on: the Rashba interaction parameter, the magnetic and electric fields, confining frequency, and temperature. The results reveal that these parameters can tune the magnetic properties of the GaAs quantum dot and flip the sign of magnetic susceptibility from negative (diamagnetic) to positive (paramagnetic) type material.

In this work, we investigate the cumulative effects of temperature, spin orbit interaction (SOI) and the magnetic field on properties of the magnetopolaron in RbCl quantum well. The Ground state binding energy (GSBE) of the magnetopolaron in RbCl QW is evaluated using the Lee Low Pine Unitary transformation (LLPUT) and the combination operation method. Numerical results show that, in addition to temperature, the spin orbit interaction affects considerably the GSBE of the magnetopolaron. Also, the transition behavior at threshold values of the temperature as well as the cyclotron frequency is considered. This study reveals that the spin orbit interaction cannot be neglected during the investigation of the nanostructure system.

The influence of a magnetic field on the Rashba spin–orbit interaction in an anisotropic quantum dot is theoretically studied, and the expression of the ground state energy of a magnetopolaron is obtained with the Pekar variational method. The ground state energy of the magnetopolaron splits into two branches due to the Rashba effect, and the splitting appears saturated phenomenon with increasing the transverse and longitudinal effective confinement lengths. Because the contribution of the magnetic field cyclotron resonance frequency to the Rashba spin–orbit splitting is a positive value, the energy spacing becomes larger as the magnetic field cyclotron resonance frequency increases. Due to the spin–orbit coupling interaction, the energy splits at zero magnetic field. The total energy is reduced due to the presence of phonons. Therefore, the polaron state is more stable than the bare electron state, and the polaron energy splitting is more stable.

Z 2 topology in two-dimensional group IVA materials has been explained by the band orders due to the crystal field splitting at the Γ point in the Brillouin zone, while spin-orbit coupling (SOC) was considered just to open a band gap. By using a multi-orbital tight-binding model, we show that the SOC induces band inversion between the conduction and valence bands at the Γ point in plumbene, which also is the case in stanene when the SOC strength increases. As a result of the band inversion, plumbene becomes a spin Chern insulator with a spin Chern number C S = 2 and, as the SOC strength increases, stanene undergoes a topological phase transition from a Z 2 topological insulator to a spin Chern insulator with C S = 2. Under a staggered AB-sublattice potential, plumbene undergoes a phase transition from the spin Chern insulator with C S = 2 to a Z 2 topological insulator with C S = 1.

Temperature dependence of anisotropic tensor susceptibility (ATS) scattering intensities of GdB4 were measured near L-edges of Gd to investigate how spin ordering affects ATS. ATS scattering intensities for L2- and L3-edges show different temperature dependence below TN. At L3-edge the intensities reflect spin order parameter while intensities at L2-edge do not show noticeable change. The difference is explained in terms of spin-orbit coupling and isotropic distribution of spin-polarized 5d states of Gd ions. Above TN ATS scattering intensities demonstrate that thermal motions enhance charge distribution anisotorpy of Gd 5d states in paramagnetic phase.

We performed microwave spectroscopy of an InAs nanowire between superconducting contacts implementing a finite-length, multi-channel Josephson weak link. Certain features in the spectra, such as the splitting by spin-orbit interactions of the transition lines among Andreev states, have been already understood in terms of non-interacting models. However, we identify here additional transitions, which evidence the presence of Coulomb interactions. By combining experimental measurements and model calculations, we reach a qualitative understanding of these very rich Andreev spectra., Comment: (6+8) pages, (4+10) figures; added figure in SM

In this paper, we consider the spin–orbit interaction (LS) as a mechanism in the high-energy double ionization of the He-atom via Compton scattering. Our calculations of the LS mechanism are based on the relativistic correction to the Coulomb interaction of the ejected electrons in the final state. The LS interaction enables the spin-triplet final state of the electrons, which is not possible in the non-relativistic approaches. We calculate the differential cross sections and their ratios for double to single ionization in the specific geometries to demonstrate the theoretical identification of the proposed LS mechanism. We analyze the LS mechanism as a function of the energy of the incident photon and the scattering angles of the photon and the Compton electron. We also compare our results with the calculations of the previous approaches.

A theoretical study is presented of the effect of an in-plane magnetic exchange field on the band structure of centrosymmetric films of noble metals and topological insulators. Based on an ab initio relativistic $\mathbf{k}\cdot\mathbf{p}$ theory, a minimal effective model is developed that describes two coupled copies of a Rashba or Dirac electronic system residing at the opposite surfaces of the film. The coupling leads to a structural gap at $\bar{\Gamma}$ and causes an exotic redistribution of the spin density in the film when the exchange field is introduced. We apply the model to a nineteen-layer Au(111) film and to a five-quintuple-layer Sb$_2$Te$_3$ film. We demonstrate that at each film surface the exchange field induces spectrum distortions similar to those known for Rashba or Dirac surface states with an important difference due to the coupling: At some energies, one branch of the state loses its counterpart with the oppositely directed group velocity. This suggests that a large-angle electron scattering between the film surfaces through the interior of the film is dominant or even the only possible for such energies. The spin-density redistribution accompanying the loss of the counterpart favors this scattering channel., Comment: 7 pages, 3 figures

The significance of the spin-orbit interaction is very well known in compounds containing heavier elements such as the rare-earth Eu ion. Here, through density functional calculations, we investigated the effect of the spin-orbit interaction on the magnetic ground state of Eu doped magnetite ($\mathrm{Fe_3O_4:Eu_{Fe}}$). By examining all possible spin alignments between Eu and magnetite's Fe, we demonstrate that Eu, which is most stable when doped at the tetrahedral site, adapts a spin almost opposite the substituted Fe. Consequently, because of smaller spin cancellation between the cations on the tetrahedral site ($\mathrm{Fe_{Tet}}$ and $\mathrm{Eu_{Tet}}$) and the cations on the octahedral sites ($\mathrm{Fe_{Oct}}$), $\mathrm{Fe_3O_4:Eu_{Fe}}$ exhibits a maximum saturation magnetisation of 9.451 $\mu_B/$f.u. which is significantly larger than that of undoped magnetite (calculated to be 3.929 $\mu_B/$f.u.). We further show that this large magnetisation persists through additional electron doping. However, additional hole doping, which may unintentionally occur in Fe deficient magnetite, can reduce the magnetisation to values smaller than that of the undoped magnetite. The results presented here can aid in designing highly efficient magnetically recoverable catalysts for which both magnetite and rare earth dopants are common materials., Comment: 12 pages, 9 figures, 3 tables

We investigate the effects of the sign of the Rashba spin-orbit coupling (RSOC) on electron transmission through a single-channel Nanowire (NW) in the quantum coherent regime. We show that, while for a finite length NW with homogeneous RSOC contacted to two electrodes the sign of its RSOC does not affect electron transport, the situation can be quite different in the presence of an inhomogeneous RSOC and a magnetic field applied along the NW axis. By analyzing transport across an interface between two regions of different RSOC we find that, if the two regions have equal RSOC signs, the transmission within the magnetic gap energy range is almost perfect, regardless of the ratio of the spin-orbit energies to the Zeeman energy. In contrast, when the two regions have opposite RSOC signs and are Rashba-dominated, the transmission gets suppressed. Furthermore, we discuss the implementation on a realistic NW setup where two RSOC regions are realized with suitably coupled gates separated by a finite distance. We find that the low-temperature NW conductance exhibits a crossover from a short distance behavior that strongly depends on the relative RSOC sign of the two regions to a large distance oscillatory behavior that is independent of such relative sign. We are thus able to identify the conditions where the NW conductance mainly depends on the sign of the RSOC and the ones where only the RSOC magnitude matters., Comment: 17 pages, 10 figures

We develop time-splitting finite-difference methods, using an implicit Backward–Euler and a semi-implicit Crank–Nicolson discretization schemes, to study the spin-orbit-coupled (SO-coupled) spinor Bose–Einstein condensates with coherent coupling in quasi-one- and quasi-two-dimensional traps. The split equations involving kinetic energy and spin-orbit-coupling operators are solved using either a time implicit Backward–Euler or a semi-implicit Crank–Nicolson method. We explicitly develop the methods for pseudospin-1/2, spin-1 and spin-2 condensates. The results for ground states obtained with time-splitting Backward–Euler and Crank–Nicolson methods are in excellent agreement with time-splitting Fourier spectral method, which is one of the popular methods to solve the mean-field models for SO-coupled spinor condensates. We confirm the emergence of different phases in SO-coupled pseudospin-1/2, spin-1 and spin-2 condensates with coherent coupling.

We theoretically investigate spin polarization for electrons in magnetically and electrically confined semiconductor microstructure, which is constructed by patterning a ferromagnetic stripe and a Schottky-metal stripe on top and bottom of GaAs/AlxGa1-xAs heterostructure, respectively. Both Zeeman interaction and spin–orbit coupling are taken into account; however, electron-spin polarization comes mainly from the latter due to a small effective g-factor for GaAs. Besides, both magnitude and sign of spin polarization can be manipulated by changing interfacial confining electric field or strain engineering, resulting in a tunable electron-spin filter for spintronics device applications.

International audience; We present a formulation and implementation of anisotropic and isotropic electronic circular dichroism (ECD) using the full semi-classical light--matter interaction operator within a four-component relativistic framework. The account of both beyond-first-order light--matter interactions and relativistic effects allows us to investigate the ECD response across the electromagnetic spectrum from optical to X-ray wavelengths where relativistic selection rules and spatial field variations gain increasing importance. We consider the isotropic and oriented ECD across the valence, sulfur L- and K-edge transitions in the simplest disulfides, H2S2 and (CH3S)2, and evaluate the influence of the full interaction by comparing to a traditional truncated formulation in the Coulomb gauge (velocity representation). Additionally, we demonstrate that in the relativistic formalism it is possible to work in the velocity representation, hence keeping order-by-order gauge-origin invariance, contrary to multipolar gauge, yet being able to distinguish electric and magnetic multipole contributions. Going beyond a first-order treatment in the wave vector is mandatory in the higher-energy end of the soft X-ray region where the consequent intensity redistribution becomes significant. While the sulfur K-edge absorption spectrum is essentially unaffected by this redistribution, the signed differential counterpart is not: at least third-order contributions are required to describe the differential absorption profile that is otherwise overestimated by a factor of about two.

Magnetic materials with high spin polarization emerge as a potential candidate in spintronic applications. The present work reports the theoretical investigation of spin-polarized electronic, structural, magnetic, and optical properties of full-Heusler Co2VZ (Z = Al, Be) alloys calculated with full-potential linearized augmented plane wave method implemented in WIEN2k code. The spin orbital coupling effect is employed, and the structures are optimized at their ground state and lattice constants and bulk moduli are calculated. A metallic behavior is observed in the majority spin carriers, and an n-type semiconducting behavior is observed in the minority spin carriers for both alloys with generalized gradient approximation. A band gap of 0.55 eV and 0.41 eV is observed in the minority spin carriers with modified Becke–Johnson (mBJ) exchange potential for Co2VAl and Co2VBe, respectively. It shows 100% spin polarization at Fermi level with mBJ potential and confirms the half metallic nature of these alloys. The structure stability is confirmed with phonon dispersion curves. The calculated magnetic moments show the major contribution of cobalt (Co) atoms in the overall magnetic behavior of both alloys. In addition, the optical parameters such as real and imaginary parts of dielectric function, refractive index, extension coefficients, optical conductivity, absorption coefficients and energy loss are also calculated. The existence of complete spin polarization endorses these alloys as a promising candidate for spintronic and opto-electronic devices.

We implement spin–orbit coupling (SOC) within the framework of semiempirical orthogonalization-corrected methods (OMx). The excited-state wavefunction is generated from configuration interaction with single excitations (CIS). The SOC Hamiltonian in terms of the one-electron Breit–Pauli operator with effective nuclear charges is adopted in this work. Benchmark calculations show that SOCs evaluated using the OMx/CIS method agree very well with those obtained from time-dependent density functional theory. As a particularly attractive application, we incorporate SOCs between singlet and triplet states into Tully's fewest switches surface hopping algorithm to enable excited-state nonadiabatic dynamics simulations, treating internal conversion and intersystem crossing on an equal footing. This semiempirical dynamics simulation approach is applied to investigate ultrafast intersystem crossing processes in core-substituted naphthalenediimides.

A new noncentrosymmetric phosphide ThIrP has been synthesized and characterized.X-ray diffraction analysis shows that this compound crystallizes in a LaPtSi-type tetragonal lattice (space group $I$4$_{1}$$md$, $Z$ = 4), whose lattice parameters are $a$ = $b$ = 4.0676(1) A $c$ = 14.3354(2) A and $V$ = 237.191(8) A$^{3}$.Moreover, ThIrP is discovered to be an intermediately coupled, type-II superconductor with possibly multiple gaps below $T_{\\rm~c}$ = 5.07 K. The upper critical magnetic field, Sommerfield coefficient, and Ginzburg-Laudau parameter are determined based on physical property measurements, which are $B_{\\rm~c2}$ = 0.83 T, $\\gamma$ = 7.5 mJ mol$^{-1}$ K$^{-2}$, and $\\kappa_{\\mathrm{GL}}$ = 7.5, respectively.The electronic band structure calculations point out nearly equal contributions of Ir and Th atoms on the density of states around the Fermi surface. In addition, the spin-orbit coupling induced band splitting reaches as large as 270 meV along the $\\Gamma$-$Z$ line. Our results suggest that ThIrP provides a platform to study the interplay between inversion-symmetry breaking, strong spin-orbit coupling, and superconductivity.

Carbon nanotubes (CNTs), helically wrapped with single-stranded DNA, have recently emerged as a spin-filtering material. The inversion asymmetric helical potential of DNA creates a spin-filtering effect (commonly known as "chirality-induced spin selectivity" or CISS), which polarizes carrier spins in the nanotube. Thus, tuning of the DNA-CNT interaction is expected to affect carrier spins in nanotubes. The CISS effect induces spin polarization, which is coupled with the carrier's momentum direction, and therefore, in one-dimensional systems, such as nanotubes, momentum flip must be accompanied by a simultaneous spin flip. This spin momentum locking can have a profound impact on charge transport in nanotubes as backscattering due to phonons and disorder will be suppressed as these mechanisms are spin-independent. Here, we report DNA-CNT spin filters in which CNTs have been functionalized with two different classes of sequences, exhibiting different degrees of interaction with the CNT. They induce different degrees of spin polarization in the channel, with significant impact on temperature-dependent charge transport and interference phenomena arising from carrier backscattering. This work raises the intriguing possibility of engineering charge transport in nanotubes

Among the perovskite oxide family, KTaO3 (KTO) has recently attracted considerable interest as a possible system for the realization of the Rashba effect. In this work, we report a novel conducting interface by placing KTO with another insulator, LaVO3 (LVO) and report planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) measurements. This interface exhibits a signature of strong spin-orbit coupling. Our experimental observations of two fold AMR and PHE at low magnetic fields (B) is similar to those obtained for topological systems and can be intuitively understood using a phenomenological theory for a Rashba spin-split system. Our experimental data show a B2 dependence of AMR and PHE at low magnetic fields that could also be explained based on our model. At high fields (~8 T), we see a two fold to four fold transition in the AMR that could not be explained using only Rashba spin-split energy spectra. Two dimensional electron gas (2DEG) at oxide interfaces is promising in modern electronic devices. Here, Wadehra et al. realize 2DEG at a novel interface composed of LaVO3 and KTaO3, where strong spin-orbit coupling and relativistic nature of the electrons in the 2DEG, leading to anisotropic magnetoresistance and planar Hall effect.

Two-dimensional (2D) Dirac-like electron gases have attracted tremendous research interest ever since the discovery of free-standing graphene. The linear energy dispersion and nontrivial Berry phase play a pivotal role in the electronic, optical, mechanical, and chemical properties of 2D Dirac materials. The known 2D Dirac materials are gapless only within certain approximations, for example, in the absence of spin-orbit coupling (SOC). Here, we report a route to establishing robust Dirac cones in 2D materials with nonsymmorphic crystal lattice. The nonsymmorphic symmetry enforces Dirac-like band dispersions around certain high-symmetry momenta in the presence of SOC. Through μ-ARPES measurements, we observe Dirac-like band dispersions in α-bismuthene. The nonsymmorphic lattice symmetry is confirmed by μ-low-energy electron diffraction and scanning tunneling microscopy. Our first-principles simulations and theoretical topological analysis demonstrate the correspondence between nonsymmorphic symmetry and Dirac states. This mechanism can be straightforwardly generalized to other nonsymmorphic materials. The results enlighten the search of symmetry-enforced Dirac fermions in the vast uncharted world of nonsymmorphic 2D materials.

Herein, the Rashba spin orbit coupling (SOC) of polar group III-VI chalcogenide XABY (A, B = Ga, In; X ≠ Y = S, Se, Te) monolayers is investigated based on density functional theory. The different electronegativities of X and Y atoms lead to an asymmetrical internal electric field in the XABY monolayer; this implies that the internal electric field between A and X is not equal to that between B and Y. Mirror symmetry breaking in the XABY monolayer induces a remarkable Rashba spin splitting (RSS) at the conduction band minimum (CBM). Moreover, it is demonstrated that an external electric field and an in-plane biaxial strain can affect the internal electric field by varying the charge distribution, and this further manipulates the RSS. Under a positive external electric field and tensile strain, the RSS at the CBM exhibits a near-linear increasing behavior, whereas under a negative external electric field and compressive strain, the RSS displays a monotonous decreasing pattern. In addition, we explored the influence of interlayer coupling and substrate on the RSS. The stacking pattern of bilayer structures has a significant impact on the RSS. The investigation of SInGaSe on the Si(111) substrate suggests that the Rashba band is situated inside the large band gap of the substrate. Overall, our investigations suggest that the polar group III-VI chalcogenides are promising candidates for future spintronic applications.

Theoretical study of coinage metal dihalides is challenging due to their complex electron correlation and relativistic effects, particularly the spin-orbit coupling (SOC) effect. Furthermore, vibrational frequencies and characters of their low-lying states are affected by the Renner-Teller effect (RTE) and pseudo-Jahn-Teller effect (PJTE). The theoretical results depend on the basis set and how the electron correlation is treated and previous results even differ qualitatively in the ground state for some silver dihalides. The equation-of-motion coupled-cluster method at the singles and doubles level (EOM-CCSD) for ionization potentials is employed in this work to calculate electron affinities and vertical excitation energies of MX2 (M = Ag, Au; X = Cl, Br and I) as well as structures, harmonic frequencies and adiabatic excitation energies for the lowest two states of these molecules. Effects of the higher level correlation, basis set as well as SOC on these results, particularly on the πu bending mode frequencies of the 2Πg state, are investigated. A new assignment for photodetachment spectroscopy of AuCl2- is proposed where contribution of the 2Δg state is considered. The ground state of AgCl2 is calculated to be the 2B2 state of the C2v structure in scalar-relativistic (SR) calculations, while the SOC quenches the RTE and PJTE and the ground state becomes the 2Π3/2g state of the D∞h structure. As for the other molecules, the ground state is calculated to be the 2Πg state in SR cases, and the 2Π3/2g state with SOC. Our results indicate that a higher level electron correlation, large basis set and SOC are important to achieve reliable results for these molecules.

This paper describes the effect of 5-nm thick platinum (Pt), aluminum (Al) and silicon oxide (SiOx) capping layers on the static and dynamic magnetic properties of 400-nm thick polycrystalline YIG films deposited on a Pt buffer layer. Both static and dynamic magnetic properties of Pt capped YIG film are totally different among all YIG films. Namely, the squareness of the magnetization curve for Pt capped YIG film increases, indicating that Pt capped YIG film is magnetically softer than other YIG films. Interestingly, the effective Gilbert damping parameter of Pt capped YIG films is about four times as large as those of other YIG films, and its value is approximately 9.52 × 10−4. However, the value of Gilbert damping is 2.55 × 10−4, 3.46 × 10−4 and 3.85 × 10−4 respectively for no capping, SiOx capping and Al capping samples respectively. This huge change in Gilbert damping parameter is mainly originating from the spin pumping effect, which arises at the interface of a material having strong spin orbit interaction such as Pt. Moreover, the enourmous increase in the value of effective anisotropic field and decrese in effective saturation magnetization indicates interface anisotropy is induced in Pt capped sample. These results suggest that the static and dynamic magnetic properties of YIG film can be controlled by selecting an appropriate capping layer.

We demonstrate that the synergistic effect of a gauge field, Rashba spin-orbit coupling (SOC), and Zeeman splitting can generate chaotic cyclotron and Hall trajectories of particles. The physical origin of the chaotic behavior is that the SOC produces a spin-dependent (so-called anomalous) contribution to the particle velocity and the presence of Zeeman field reduces the number of integrals of motion. By using analytical and numerical arguments, we study the conditions of chaos emergence and report the dynamics both in the regular and chaotic regimes. {We observe the critical dependence of the dynamic patterns (such as the chaotic regime onset) on small variations in the initial conditions and problem parameters, that is the SOC and/or Zeeman constants. The transition to chaotic regime is further verified by the analysis of phase portraits as well as Lyapunov exponents spectrum.} The considered chaotic behavior can occur in solid state systems, weakly-relativistic plasmas, and cold atomic gases with synthetic gauge fields and spin-related couplings., Comment: 8 pages, 7 figures

Both LaAlO3 and BiAlO3 are isostructural, isoelectronic and band insulators. Therefore, in analogy to the LaAlO3/SrTiO3 heterostructure, a quasi two dimensional electron gas (q-2DEG) could be anticipated in BiAlO3/SrTiO3 heterostructures. Our density functional theory based scalar relativistic calculations show that BiAlO3/SrTiO3 heterostructures remain insulating for a BiAlO3 film thickness up to 5 unit cells. However, with spin orbit coupling included in the crystal Hamiltonian, we find a thickness dependent insulator to metal transition for BiAlO3/SrTiO3 heterostructures. However, unlike the Ti3+/Ti4+ electronic reconstruction in LaAlO3/SrTiO3, the conductivity in BiAlO3/SrTiO3 is found to originate from the subsurface Bi 6p states. The results suggest that the properties of q-2DEG in BiAlO3/SrTiO3 can be controlled using an external electric field, leading to a wide range of solid state applications.

We have presented the single particle spectrum for a particle in a mean field of isotropic harmonic oscillator with l.s coupling based on our semiclassical approach. It has been seen that this spectrum, without l.s coupling, exactly matches with the quantum mechanical one (without nuclear constraints). In this case, periodicity conditions give only pendulating orbits coinciding with l=0 axis, which fully support the observations reported by Bohr and Mottelson [28]. The orbits with l>0 are generated by reflecting the particle from the nuclear surface, instead of infinity, which is the usual nuclear constraint. The mean field strength is fixed by virial theorem. The resulting spectrum compares reasonably with the quantum spectrum for a particle enclosed in a perfectly reflecting walls. The variation of particle number with energy help us to identify the significant quantum numbers n and l in this semiclassical method. Finally, the l.s coupling splits each level and the splitting width of these level compares well with that of nuclear splitting. Thus the complete nuclear shell model (with magic numbers) is reproduced without any fitting parameter.

The field dependences of the magnetoresistance for germanium whiskers with gallium doping concentration of 2 ⋅ 1017 cm-3 were studied in the magnetic field range 0–14 T at temperature 4.2 K under compressive strain up to 0.2%. The strain influence on a spin-orbit splitting on the valence band spectrum was studied. As a result, the effective mass and the energies of spin-orbit splitting for light and heavy holes were found under the compressive strain according to kp method. From an analysis of the Shubnikov—de Haas magnetoresistance oscillations the effective mass of heavy holes mc = 0.25 m0 was calculated. The spin-orbit splitting energy of heavy holes ΔHH = 15 meV, the Lande factor in direction [111] g* = 4.8 as well as the Rashba cubic parameter of spin-orbit interaction β S O = 1 ⋅ 10 − 28 eV ⋅ m 3 were found due to the studying of longitudinal magnetoconductance in strained Ge whiskers at low temperatures. The appearance of negative magnetoresistance in the magnetic field range up to 7 T likely results from the effect of charge carrier interaction.The field dependences of the magnetoresistance for germanium whiskers with gallium doping concentration of 2 ⋅ 1017 cm-3 were studied in the magnetic field range 0–14 T at temperature 4.2 K under compressive strain up to 0.2%. The strain influence on a spin-orbit splitting on the valence band spectrum was studied. As a result, the effective mass and the energies of spin-orbit splitting for light and heavy holes were found under the compressive strain according to kp method. From an analysis of the Shubnikov—de Haas magnetoresistance oscillations the effective mass of heavy holes mc = 0.25 m0 was calculated. The spin-orbit splitting energy of heavy holes ΔHH = 15 meV, the Lande factor in direction [111] g* = 4.8 as well as the Rashba cubic parameter of spin-orbit interaction β S O = 1 ⋅ 10 − 28 eV ⋅ m 3 were found due to the studying of longitudinal magnetoconductance in strained Ge whiskers at low temperatures. The appearance of negative magnetoresistance in the magnetic field range up to 7 T lik...

It is shown, based on the density functional theory (DFT) calculations, that weak van der Waals interaction between monolayers of Pb and MoTe2 introduce a symmetry breaking that gives rise to spin polarized interface states. This is a departure from a conventional picture of band spin splitting in the adsorption systems as it is usually associated with the strong surface interactions e.g. covalent bonds, which results in electronic charge asymmetry in the vicinity of the adatom's nuclei. The analysis based on the effective Hamiltonian within the orbital-angular-momentum approach to the Rashba effect indicates that the observed spin splitting originates directly from the atomic spin-orbit coupling, with the orbital angular momentum unquenched due to broken inversion symmetry.

Triplet–triplet upconversion, in which two triplet excitons are converted to one singlet exciton, is a well-known approach to exceed the limit of electroluminescence quantum efficiency in conventional fluorescence-based organic light-emitting diodes. Considering the spin multiplicity of triplet pairs, upconversion efficiency is usually limited to 20%. Although this limit can be exceeded when the energy of a triplet pair is lower than that of a second triplet excited state, such as for rubrene, it is generally difficult to engineer the energy levels of higher triplet excited states. Here, we investigate the upconversion efficiency of a series of new anthracene derivatives with different substituents. Some of these derivatives show upconversion efficiencies close to 50% even though the calculated energy levels of the second triplet excited states are lower than twice the lowest triplet energy. A possible upconversion mechanism is proposed based on the molecular structures and quantum chemical calculations., Though triplet-triplet upconversion is a promising strategy for designing new deep blue-emitting organic materials, maximizing the efficiency of this process remains difficult. Here, the authors report the upconversion efficiency in anthracene derivatives based on a spin-orbit coupling mechanism.

Generating valley polarization is the key process in valleytronics. In this work, the valley polarization properties of WSSe induced by transition-metal (TM) doping or adsorption are investigated through first principles calculations. Both the doping and adsorption of TM atoms can induce valley polarization after considering spin orbit coupling in the WSSe system. Different impurity energy levels will be introduced by the TM doping or adsorption, and the hybridization between these impurity energy levels and the highest valence band of WSSe will influence the valley polarization properties. Big valley polarization can be obtained in the cases of V doping or Cr adsorption on the Se-surface in WSSe. Valley polarization can be induced and controlled by TM doping or adsorption in WSSe, which contributes to anomalous valley Hall effects.

Two different kinds of spin-orbit (SO) coupling are often investigated theoretically and experimentally in atomic Bose-Einstein condensates (BECs), namely, Rashba and Dresselhaus SO couplings. We show that ground states for these two SO-coupled BECs share lots of similarities and it is impossible to distinguish them from the observation of ground states. We find that an Ioffe-Pritchard magnetic field can be utilized as a tool to distinguish them. In the presence of the Ioffe-Pritchard magnetic field, ground states manifest distinctively for the Rashba and Dresselhaus SO-coupled BECs.

We study the spin transport in bilayer graphene nanoribbons (BGNs) in the presence of Rashba spin-orbit interaction (SOI) and external gate voltages. It is found that the spin polarization can be significantly enhanced by the interlayer asymmetry or longitudinal mirror asymmetry produced by external gate voltages. Rashba SOI alone in BGNs can only generate current with spin polarization along the in-plane y direction, but the polarization components can be found along the x, y and z directions when a gate voltage is applied. High spin polarization with flexible orientation is obtained in the proposed device. Our findings shed new light on the generation of highly spin-polarized current in BGNs without external magnetic fields, which could have useful applications in spintronics device design.

The property of matter-wave vector solitons in a spin-1 Bose-Einstein condensate with spin-orbit and Zeeman couplings is investigated by multiscale perturbation method. The excitation spectrum and the corresponding state vectors of the system are obtained analytically, and they can be adjusted by the parameters of the system. The bright and dark vector solitons are formulated by reducing the three-component coupled Gross-Pitaeviskii equations to a standard nonlinear Schrodinger equation, which has the solutions of the bright and dark solitons with positive or negative mass depending on the product of the effective dispersive and nonlinear coefficients. The moving vector solitons are demonstrated by adjusting specific momentum near the energy minimum. Finally, the magnetized features of the vector solitons are discussed by the spin polarization of the system.