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The electrical manipulation of magnetization is appealing to the relevant experiment and spintronic device. In this paper, we focus on the electrical and magnetic properties of a thin film cleaved from the nonmagnetic half-Heusler compound CoTiSb. By means of the first-principles calculations, we find that the surface of TiSb termination possesses ferrimagnetism with a magnetic moment of 0.35 (0.49) μB per unit cell without (with) Hubbard U, which can persist below the Curie temperature of 48 (54) K. What is more, such a surface magnetism can be tuned to nonmagnetism by gate-induced hole doping with a concentration of 2.83 × 1014 (3.55 × 1014) cm−2. This magnetic tunability of the CoTiSb slab provides a platform to realize the pseudo-spin valve with both the magnetic electrodes and nonmagnetic space layer made of the same material without hetero-interfaces. [ABSTRACT FROM AUTHOR]

In the process of ship collision avoidance decision making, steering collision avoidance is the most frequently adopted collision avoidance method. In order to obtain an effective and reasonable steering angle, this paper proposes a decision-making method for ship collision avoidance based on improved cultural particle swarm. Firstly, the ship steering angle direction is to be determined. In this stage, the Kalman filter is used to predict the ship's trajectory. According to the prediction parameters, the collision risk index of the ship is calculated and the situation with the most dangerous ship is judged. Then, the steering angle direction of the ship is determined by considering the Convention on the International Regulations for Preventing Collisions at Sea (COLREGs). Secondly, the ship steering angle is to be calculated. In this stage, the cultural particle swarm optimization algorithm is improved by introducing the index of population premature convergence degree to adaptively adjust the inertia weight of the cultural particle swarm so as to avoid the algorithm falling into premature convergence state. The improved cultural particle swarm optimization algorithm is used to find the optimal steering angle within the range of the steering angle direction. Compared with other evolutionary algorithms, the improved cultural particle swarm optimization algorithm has better global convergence. The convergence speed and stability are also significantly improved. Thirdly, the ship steering angle direction decision method in the first stage and the ship steering angle decision method in the second stage are integrated into the electronic chart platform to verify the effectiveness of the decision-making method of ship collision avoidance presented in this paper. Results show that the proposed approach can automatically realize collision avoidance from all other ships and it has an important practical application value. [ABSTRACT FROM AUTHOR]

Electron transport through a parallel double-dot structure with four terminals is theoretically studied. Introduction of a local Rashba spin-orbit interaction results in a distinct spin polarization of the electrons being transported through the structure. More interestingly, we find that the intradot electron interaction can influence the spin-polarized electron transport spectrum in a nontrivial way. It can enhance or reverse the electron spin polarization, depending on the strengths of the electron interaction. The underlying quantum interference that gives rise to such results is clarified by the analysis of the phase relation among the electron transmission paths. [ABSTRACT FROM AUTHOR]

The two‐dimensional (2D) materials InX (X = O, Se), experimentally available thus far, can become a ferromagnetic half metal under hole doping, though the charge neutral states of them are nonmagnetic semiconductors. Based on such an electronic characteristic, a theoretical model of magnetic tunnel junction (MTJ) is proposed composed only of one of the 2D InX. In doing so, the two semi‐infinite pieces of 2D InX in the half‐metallic state is assumed as the opposite electrodes which are separated by a strip of the same material but in its nonmagnetic state. Owing to the 2D nature of InX, the half metal electrodes of the InX device induced by hole doping can be achieved by using split gating technique. The numerical simulations identify a proper hole doping concentration, at which 100% tunneling magnetoresistance (TMR) ratios can be realized, accompanying an appreciable conductance of majority spin electron under parallel magnetization configuration. Under a finite bias voltage, the TMR ratio remains high. Therefore, the proposed device model is an ideal candidate for future spintronics applications. It enables electrical control of TMR and circumvents the detriment of hetero‐interface disorder inevitable in conventional MTJs. [ABSTRACT FROM AUTHOR]

The thermodynamic simulation analysis of carbon monoxide water gas shift in rich hydrogen was researched by using the method of Gibbs free energy minimization with Aspen plus software. For the purpose of purifying trace amount of CO in hydrogen, two raw gas compositions, 1%CO–99%H 2 and 1%CO–24%CO 2 –75%H 2 , were purposely selected, and the influences of water to gas molar ratio (1–7) and transformation temperature (40–280 °C) were investigated. The results showed similar variation law as compared with the water gas shift of a pure CO gas. When the transformation temperature increased, the chemical equilibrium shifted toward the reverse direction, resulting in decreased CO equilibrium conversion; when the water to gas molar ratio increased, the CO conversion increased. The results also showed that CO 2 had great negative effects on CO conversion compared with H 2. For the CO/H 2 feed gas, it was concluded that it was possible to reduce the 1% CO content to 100 ppm at 120 °C with the use of the best low-temperature catalyst reported in literature. If we want to further reduce the trace amount of CO in hydrogen to 10 ppm, it is necessary to develop ultra-low temperature catalysts that are highly active below 70 °C. • Simulation of CO water gas shift reaction in excess H 2 and H 2 /CO 2. • CO 2 has a great influence on CO conversion compared to H 2. • 1%CO in H 2 reduced to 100 ppm with the available catalyst at 120 °C. • To reduce CO to 10 ppm, it is necessary to develop catalysts below 70 °C. [ABSTRACT FROM AUTHOR]

Abstract: Optical conductivity of a graphene sheet subject to a one-dimensional cosinusoidal potential is studied. We find that the optical conductivity can be tuned by the strength of the superlattice potential. When this strength is within a certain range the terahertz conductivity can be enhanced by two orders of magnitude. [ABSTRACT FROM AUTHOR]

Abstract: Electron transport properties in a parallel double-quantum-dot structure with three terminals are theoretically studied. By introducing a local Rashba spin–orbit coupling, we find that an incident electron from one terminal can select a specific terminal to depart from the quantum dots according to its spin state. As a result, spin polarization and spin separation can be simultaneously realized in this structure. And spin polarizations in different terminals can be inverted by tuning the structure parameters. The underlying quantum interference that gives rise to such a result is analyzed in the language of Feynman paths for the electron transmission. [Copyright &y& Elsevier]

Abstract: The contact conductance between graphene and two quantum wires which serve as the leads to connect graphene and electron reservoirs is theoretically studied. Our investigation indicates that the contact conductance depends sensitively on the graphene-lead coupling configuration. When each quantum wire couples solely to one carbon atom, the contact conductance vanishes at the Dirac point if the two carbon atoms coupling to the two leads belong to the same sublattice of graphene. We find that such a feature arises from the chirality of the Dirac electron in graphene. Such a chirality associated with conductance zero disappears when a quantum wire couples to multiple carbon atoms. The general result irrelevant to the coupling configuration is that the contact conductance decays rapidly with the increase of the distance between the two leads. In addition, in the weak graphene-lead coupling limit, when the distance between the two leads is much larger than the size of the graphene-lead contact areas and the incident electron energy is close to the Dirac point, the contact conductance is proportional to the square of the product of the two graphene-lead contact areas, and inversely proportional to the square of the distance between the two leads. [Copyright &y& Elsevier]

Abstract: In previous calculations about the electronic transport properties through a gated region in graphene, a step-like potential is frequently adopted to mimic the gated barrier in two different theoretical models, i.e. the tight-binding model and the Dirac equation description. Our theoretical investigation indicates that the same step-like potential but used in the two distinct models are not equivalent. In the Dirac equation, a step-like potential can not reflect the normally incident electron due to Klein paradox. However, in tight-binding model, such a potential includes the scattering terms which can destroy the pseudo-spin conservation to cause a finite reflection. Thus, the electron transmission is not perfect. [Copyright &y& Elsevier]

Abstract: Electron transport through a triple-quantum-dot ring with three terminals is studied theoretically. By introducing the local Rashba spin–orbit interaction in an individual quantum dot, we find that an incident electron from one terminal can select a specific terminal to depart from the quantum dot ring according to its spin state. As a result, spin polarization and spin separation can be simultaneously realized in this structure. [Copyright &y& Elsevier]

Abstract: The influence of Rashba spin–orbit coupling on the Fano lineshape of the conductance spectrum in a T-shaped double quantum dot structure is theoretically studied. By second-quantizing the electron Hamiltonian in this structure, it is found that the Rashba interaction brings about a spin-flip interdot hopping term. With the enhancement of the Rashba interaction, this term separates the two resonant peaks in the conductance spectrum from each other. More importantly, it causes the broadening of the narrow Fano peak, and the narrowing of the broader peak. Finally, the asymmetric Fano lineshape changes into a symmetric profile in the global conductance spectrum. [Copyright &y& Elsevier]

Abstract: When a quantum dot in the Kondo regime couples to two leads (the conduction electron reservoirs) indirectly through intermediate electron levels, two features are noteworthy concerning the Kondo effect. First, the Kondo peak in the spectrum of local density of states becomes narrower as the coupling to the leads is much larger than the interdot coupling, which is just opposite to the case of direct dot-lead coupling. Secondly, the increment of the coupling to the leads and the deviation of the intermediate levels from the Fermi level can effectively facilitate the formation of the negative differential conductance. [Copyright &y& Elsevier]

Abstract: We carry out a comprehensive analysis of Fano effect in electronic transport process through a parallel double quantum dot (QD) structure. First, we establish an expression of the linear conductance in the standard Fano form. This expression provides a uniform way to explain the presence of the Fano antiresonance (or a lack of thereof) in various double QD structures. Then, by virtue of the language of Feynman path, we find that there are infinite electron transmission paths to contribute to the Fano interference. In the absence of a magnetic field, the high-order paths play a nontrivial role in the formation of the Fano lineshape. Finally, we find that it is possible to eliminate the contributions of all the high-order paths by tuning the magnetic field to some specific values. Thus, just two lowest-order Feynman paths remain. Only in such a case, the Fano effect can be unambiguously understood to arise from a quantum interference between a resonant and a nonresonant paths. [Copyright &y& Elsevier]

Abstract: By means of the non-equilibrium Green function technique, the electronic transport through an N-quantum-dot chain is theoretically studied. By calculating the linear conductance spectrum and the local density of states in quantum dots, we find the resonant peaks in the spectra coincides with the eigen-energies of the N-quantum-dot chain when the dot-lead coupling is relatively weak. With the increase of the dot-lead coupling, such a correspondence becomes inaccurate. When the dot-lead coupling exceeds twice the interdot coupling, such a mapping collapses completely. The linear conductance turn to reflect the eigen-energies of the - or -quantum dot chain instead. The two peripheral quantum dots do not manifest themselves in the linear conductance spectrum. More interestingly, with the further increase of the dot-lead coupling, the system behaves just like an - or -quantum dot chain in weak dot-lead coupling limit, since the resonant peaks becomes narrower with the increase of dot-lead coupling. [Copyright &y& Elsevier]

Abstract: The I–V spectrum of electronic transport through a quantum dot chain is calculated by means of the nonequilibrium Green function technique. In such a system, two arbitrary quantum dots are connected with two electron reservoirs through leads. When the dot-lead coupling is very weak, a series of discrete resonant peaks in electron transmission function cause staircase-like I–V characteristic. On the contrary, in the relatively strong dot-lead coupling regime, stairs in the I–V spectrum due to resonance vanish. However, when there are some dangling quantum dots in the chain outside two leads, the antiresonance which corresponds to the zero points of electron transmission function brings about novel staircase characteristic in the I–V spectrum. Moreover, two features in the I–V spectrum arising from the antiresonance are pointed out, which are significant for possible device applications. One is the multiple negative differential conductance regions, and another is regarding to create a highly spin-polarized current through the quantum dot chain by the interplay of the resonance and antiresonance. Finally, we focus on the role that the many-body effect plays on the antiresonance. Our result is that the antiresonance remains when the electron interaction is considered to the second order approximation. [Copyright &y& Elsevier]

Electronic transport through a one-dimensional quantum dot array is theoretically studied. In such a system both electron reservoirs of continuum states couple with the individual component quantum dots of the array arbitrarily. When there are some dangling quantum dots in the array outside the dot(s) contacting the leads, the electron tunneling through the quantum dot array is wholly forbidden if the electron energy is just equal to the molecular energy levels of the dangling quantum dots, which is called as antiresonance of electron tunneling. Accordingly, when the chemical potential of the reservoir electrons is aligned with the electron levels of all quantum dots, the linear conductance at zero temperature vanishes if there are odd number dangling quantum dots; Otherwise, it is equal to 2e2/h due to resonant tunneling if the total number of quantum dots in the array is odd. This odd–even parity is independent of the interdot and the lead–dot coupling strength. [Copyright &y& Elsevier]

By assuming several different analytical forms of correlation function for the interface roughness in a quantum well, the influence of interface roughness scattering on the electronic transport in the presence of a magnetic field is investigated. It is found that the roughness-limited conductivities are mainly determined by the behaviour of the correlation functions in Fourier space within the range of inverse magnetic length. Thus the electronic magnetotransport property sensitively depends on the detail of the roughness correlation function in the case of a large magnetic field. On the other hand, when the magnetic length is much larger than the roughness correlation length, which usually corresponds to the case of a relatively weak magnetic field, the conductivities calculated by different forms of roughness correlation function do not show a notable difference from each other. [ABSTRACT FROM AUTHOR]

The conductivity is calculated in lateral superlattices with weak disorder in the periodic potential by solving a Boltzmann equation exactly. A singular behavior of the distribution function due to anisotropic nature of scattering potential and diffuse Bragg scattering leads to a commensurate oscillation in the direction both parallel and perpendicular to the superlattice as well as a huge anisotropy. [Copyright &y& Elsevier]

Anomalies present at zero energy are shown to give rise to a peculiar and singular behavior of the dynamical and static conductivity in two-dimensional (2D) lattices having the structure of 2D graphite. [Copyright &y& Elsevier]

The CoFeTiSi compound is an experimentally existing half-metallic ferromagnetic Heusler compound with a Curie temperature higher than room temperature. By replacing the Si atom with Al, we can obtain a narrow bandgap semiconductor CoFeTiAl. The lattice mismatch between CoFeTiSi and CoFeTiAl is very small, which serves as motivation for constructing a CoFeTiSi/CoFeTiAl/CoFeTiSi magnetic tunnel junction. In this junction, CoFeTiSi and CoFeTiAl are used as electrode and barrier layers, respectively. The optimal device structure can be achieved simply by replacing the Si atoms in the barrier region with Al atoms. Through the use of a b i n i t i o atomic thermodynamics, we have found that this device structure is more stable compared to a junction formed by the same two compounds with an alternative interface. Transport calculations reveal that this junction can achieve a high tunneling magnetoresistance ratio at room temperature and exhibit a large transmission coefficient. These characteristics make the CoFeTiSi/CoFeTiAl/CoFeTiSi magnetic tunnel junction an ideal candidate for future spintronic applications. [Display omitted] • An all-Heusler MTJ which can achieve a high TMR at RT is proposed theoretically. • The stable normal atomic order at the interface minimizes the interface disorder. • The MTJ device achieves a high T P ↑ that is easy to detect. [ABSTRACT FROM AUTHOR]

Electronic transport through a triple-quantum-dot ring with three terminals is theoretically studied. By introducing local Rashba spin-orbit interaction on an individual quantum dot, we calculate the charge and spin currents in one lead. We find that a pure spin current without an accompanying charge current appears even at zero magnetic field case. The polarization direction of the spin current can be inverted by altering the bias voltage. In addition, by tuning the magnetic field strength, the charge and spin currents reach their respective peaks alternately. [ABSTRACT FROM AUTHOR]

Manipulating magnetism by electrical means is a very effective method to realize ultra-low power spintronic-integrated circuits. In this work, based on first-principles calculations, we demonstrate that the recently successfully fabricated two-dimensional semiconductor material, InO monolayer, can be tuned to the half-metallic state by applying a gate voltage to generate hole doping. Such a ferromagnetic state is independent of the partially occupied d - or f -orbital, it is associated with a narrow valence band. Our work provides theoretical guidance for the experimental adjustment of two-dimensional magnetic semiconductor, especially two-dimensional half-metallic material. • Gate voltage induces transition from paramagnetic to ferromagnetic phase in 2D InO. • Resulting half-metallic state holds significant potential for spintronics devices. • Electrical manipulation of magnetism is effective for ultra-low-power spintronics. [ABSTRACT FROM AUTHOR]

By applying a symmetric dipolar spin battery in a parallel-coupled quantum-dot (QD) structure, the spin accumulation in the QDs is investigated. We find that the spin accumulation can be achieved via electrically adjusting the left-right antisymmetry of the QD-lead couplings or introducing different magnetic fluxes through the sub-rings of this system. And, the spin accumulation properties are closely dependent on the number of QDs in this structure. Compared with the electrical method, the magnetic method is more efficient to manipulate the spin accumulation. When the intradot Coulomb interaction is considered, the electrically induced spin accumulation is somewhat suppressed, but in the magnetic method the spin accumulation is efficiently enhanced. We believe that the results can be observed in the experiment of spintronics, which provides an alternative scheme for spin manipulation. [ABSTRACT FROM AUTHOR]

The linear conductance spectrum of a metallic graphene junction formed by interconnecting two gapless graphene nanoribbons is calculated. A strong conductance suppression appears in the vicinity of the Dirac point. We found that such a conductance suppression arises from the antiresonance effect associated with an edge state localized at the zigzag-edged shoulder of the junction. The conductance valley due to the antiresonance is rather robust in the presence of the impurity and vacancy scattering. Also the center of the conductance valley can be readily tuned by an electric field exerted on the wider nanoribbon. [ABSTRACT FROM AUTHOR]

In order to find a method to synthesize spinel solid solution at low temperature, in this paper, pseudo-boehmite and copper nitrate were used as raw materials, and citric acid was used as accelerator for the first time, the Cu 1−x Al 2.5 spinel solid solutions were synthesized by ball milling treatment of the solid mixture and then calcined at elevated temperatures. The obtained materials were characterized by X-ray diffraction (XRD), Brunner−Emmett−Teller (BET) measurements, H 2 -temperature programmed reduction (H 2 -TPR), infrared (IR) and thermogravimetric methods (TG), and the mechanism of citric acid promoting the synthesis of the spinel solid solution was suggested. The results show that an optimal amount of citric acid can significantly promote the formation of the spinel structure, thus substantially decreasing the synthetic temperature from the above 900 °C–700 °C. At 700 °C, the preparation without the accelerator resulted in small amount of the spinel solid solution, while the use of accelerator gave rise to 82.96% spinel solid solution. Importantly, the Cu 1−x Al 2.5 spinel solid solution prepared at 700 °C demonstrates the best sustained release catalytic performance, and the catalytic activity reached more than 90% and remained stable within 50 h. The findings of this report might be provide guidance for the solid phase preparation of catalysts at relatively lower temperatures, thus facilitating the commercialization of the sustained release catalyst system. For the preparation of Cu–Al spinel by ball milling, citric acid was used as an accelerator for the first time, effectively decreasing the synthetic temperature. [Display omitted] • Citric acid was used as an accelerator for the first time. • The synthetic temperature of Cu–Al spinel by was decreased. • Possible mechanism for such an acceleration has been suggested. • The obtained solid solution can be used as a sustained release catalyst. [ABSTRACT FROM AUTHOR]

Graphene has intrinsic edge states localized at zigzag edge or lattice defect. Helical boundary states can also be established in such a two-dimensional carbon material at the boundary of topological insulator (TI) phase realized by the extrinsic Rashba spin–orbital coupling (SOC) in gated bilayer graphene. We theoretically investigate the interaction between these two kinds of edge (boundary) states when they coexist in a bilayer graphene. We find that this interaction gives rise to some very interesting results. In a zigzag edged nanoribbon of bilayer graphene, it is possible that the TI helical state does not localize at the TI phase boundary. Instead it moves to the nanoribbon edge even though the SOC is absent therein. In a bulk lattice of bilayer graphene embedded with two line defects, the numbers of helical state subbands at the two line defects are not equal to each other. In such a case, the backscattering lacking is still forbidden since the Kramers pairs are valley polarized. [ABSTRACT FROM AUTHOR]

In this study, we investigate the spin-dependent electron transport properties of a zigzag silicene nanoribbon (ZSiNR) by using spin-polarized density functional theory and the non-equilibrium Green's function method. The results show that such a ZSiNR with an FM configuration exists the perfect dual spin filtering and dual spin diode effects when the bias voltage was applied. These phenomena still exist in ZSiNRs with different widths. As the ribbon width increases, the progressively smaller bias voltage is required to trigger a polarized current. Therefore, such a ZSiNR in FM configuration is a good candidate for spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract: It was recently reported that a kind of graphene line defect can be fabricated in a controllable experimental way. In the present work we theoretically investigate the band structure and the electronic transport properties of a graphene superlattice formed by embedding periodically line defects in the graphene lattice. Based on the calculated results, we suggest that such a superlattice can be used as a quantum wire array which can carry much larger current than a single graphene nanoribbon. A remarkable advantage of this superlattice over other quantum wires is that the electronic transport in it is insensitive to scattering effects except that the scattering potential range is smaller than the graphene lattice constant. Moreover, we find that the anisotropy of the Dirac cone presented in this superlattice has a nontrivial influence on the universal minimal conductivity and the sub-Poissonian shot noise of graphene. [Copyright &y& Elsevier]

Abstract: We develop a tight-binding theory to study the electronic transport through an extended line defect in monolayer graphene. After establishing an analytical expression of the transmission probability, we clarify the following issues concerning the valley polarization in the electronic transport process. Firstly, we find that the valley polarization is robust in the total linear dispersion region. More interestingly, we find that the lattice deformation around the line defect play an important role in tuning the incident angle for complete transmission. Finally, we indicate that next nearest neighbor interaction only causes a small suppression to the valley polarization. [Copyright &y& Elsevier]

Abstract: In this work, we report a theoretical study of the electronic transport through a step-shaped graphene nanoribbon by the tight-binding method. We found that the conductance suppression near the Dirac point is pervasive, and the top boundary configuration is irrelevant; this arises from the antiresonance effect associated with an edge state localized at the transition edge of the top layer of graphene nanoribbon. In addition, the conductance can be easily tuned from zero to unity by a gate bias in the bilayer graphene nanoribbon, this feature will help us to realize the electric nanoswitch. [Copyright &y& Elsevier]

Abstract: We investigate the electronic transport through the metallic armchair T-shaped graphene nanoribbon. We found that the conductance spectrum exhibits a well-defined insulating band around the Dirac point. Our calculation also indicates that the defect can destroy the edge state localized at the zigzag-edged shoulder of the junction. When the concentration of the vacancies of each edge is about , a notable feature is the conductance insulating band can be completely eliminated. And such a conclusion is independent of the size of the shoulder. [Copyright &y& Elsevier]

The multi-ship encounter situation at sea is characterized by high complexity and uncertainty, which is a big challenge for both traditional ships and the new autonomous ships. In order to make reasonable navigation decisions and perform well under multi-ship encounter situation, it is necessary to grasp the current scenario correctly and intelligently. Therefore, in this paper, an adaptive understanding model for multi-ship encounter situation is proposed. The core function of this model is to infer the navigation intention of other target ships under the same situation. This model is mainly composed of two sub-models. One is the ship encounter situation analysis model, which realizes the cognition of the whole encounter scenario from the global perspective by maintaining the "double matrix". The second is the ship navigation intention inference model, the key part of the model is a set of well-designed fuzzy inference system. The output of the encounter situation analysis model is the input of the intention inference model, and these two models are closely linked to form a unified whole. This model is verified by both simulation-based and real scenario-based experiments, the results show that this model can perform well under the complex multi-ship encounter situation. Moreover, some necessary discussion and analysis for this inference model are also stated at the end of this paper, in the future, we expect that this model can be applied in real situations. ● A novel multi-ship encounter situation adaptive understanding model is proposed. ● The whole encounter scenario can be analyzed from the global perspective by the "double-matrix". ● The core function of this model is to infer the navigation intention of other ships under the same encounter situation. ● Both the simulation and real scenario-based experiments are conducted so as to test and verify the effectiveness of this model. [ABSTRACT FROM AUTHOR]

Within the theoretical framework of Kubo linear response theory as well as the self-consistent Born approximation(SCBA), we perform a comparative study about the Hall conductivities of a Dirac semimetal(DSM) subject to, respectively, the intra- and inter-valley scattering. By calculating the Hall conductivity as a function of Fermi level, we find that when the Fermi level lies in the region around the Dirac node, the Hall conductivities between the two cases, i.e. subject to intra- and inter-valley scattering respectively, do not show appreciable difference, regardless of the scattering strength. As the Fermi level goes away from the Dirac node, the Hall conductivity in the case of inter-valley scattering is smaller than that in the case of intra-valley scattering if the scattering has relatively weak or moderate strength. In contrast, as scattering strength increases further, the Hall conductivity spectra between the two cases look almost identical no matter whether the Fermi level is close to or far away from the Dirac node. The underlying physics of these numerical results is that the Fermi surface has nontrivial contribution to the Hall conductivity in the case of weak or moderate scattering. However, in the case of strong scattering, it becomes much smaller than the contribution arising from all the occupied states. In addition, our study indicates that the cone tilt brings about the effective enhancement of Hall conductivity of DSMs. • For the cases of weak or moderate scattering, the Hall conductivity in the case of intra-valley scattering is almost indistinguishable from that of inter-valley scattering around the Dirac node. However, as the Fermi level goes away from the Dirac node, they becomes appreciably different. • As scattering strength increases further, the difference between the two kinds of Hall conductivity becomes indistinguishable no matter whether the Fermi level is close to or far away from the Dirac node. • The cone tilt brings about a sizable enhancement of Hall conductivity of DSMs for both intra- and inter-valley scattering. [ABSTRACT FROM AUTHOR]

Based on density functional theory, we study the intrinsic anomalous Hall conductivity (AHC) of monolayer (ML) CrI 3 in different magnetic configurations. We find that ML CrI 3 in both the in-plane and off-plane ferromagnetic (FM) states hosts significant AHC, with quantum plateaus occurring at topologically nontrivial bandgaps. In the in-plane FM state, the AHC of ML CrI 3 depends sensitively on the magnetization direction. First, the sign of AHC can be inverted whenever the magnetization angle increases by 60 °. Second, the AHC vanishes if the magnetization angle is equal to the odd times of 30 °. By doping electrons and applying moderate strain, one can switch the magnetic ground state between the off- and in-plane FM states and manipulate the magnitude and sign of the AHC. Based on these features of AHC of ML CrI 3 , we propose a theoretical model to realize the functions of spintronic devices such as the reversible spin transport, magnetic sensors, or magnetic read-in head. [ABSTRACT FROM AUTHOR]

Highlights • Cu 2 Si nanoribbons with zigzag edges have flat bands of edge states. • Interaction between the edge states can induce sizable magnetism in the ribbon. • Carrier doping can induce sizable magnetism in the ribbon too. • Carrier doping can further control the real space distribution of magnetic moment. Abstract The surface states of three dimensional topological nodal line semimetal (TNLSM) form a flat band within the projection of the closed nodal line onto the surface. Such a flat band implies a singular surface density of states which, if close to the Fermi energy, is apt to induce a magnetic phase transition. Similar physics is expected in a two-dimensional (2D) TNLSM. In the framework of density functional theory, we study the edge states of Cu 2 Si monolayer which is currently an experimentally feasible sample of 2D TNLSM. We find that the flat bands attached to two kinds of zigzag edges of Cu 2 Si are very close to the Fermi energy. Moreover, we explore the possible magnetism of Cu 2 Si nanoribbons terminated by these zigzag edges. We find that a narrow ribbon has ferromagnetic ground states with sizable magnetic moments, owing to the interaction between the edge states localized at the opposite edges. In addition, carrier doping in a nanoribbon can induce the transition between the ferromagnetic and nonmagnetic states. More interestingly, the magnetic moment distribution in real space from one to another edges can be readily modulated by the carrier doping. Our study indicates that Cu 2 Si nanoribbons with controllable magnetism provide a new platform to realize the device functions of spintronics. [ABSTRACT FROM AUTHOR]

Highlights • Stability and electronic properties of hydrogenated BC 2 N sheets are investigated. • The BC 2 NH sheets present the ferromagnetic ground states. • The system can be transitioned from semiconductor to half-metal by choosing the appropriate external strain. Abstract Density functional theory has been used to study the electronic and magnetic properties as well as the stability on the hydrogenated BC 2 N sheets. It is found that two different structures (BC 2 NH-I and BC 2 NH-II) with the ferromagnetic ground states can be formed when removing the H atoms from one side of semi-hydrogenated BC 2 N sheet. By applying tensile strain, both of their magnetisms are robust to 2.0 μ B. However, the magnetisms are sensitively changed by compressive strain larger than −6%. The BC 2 NH-I system can be transitioned from semiconductor to half-metal and then to metal when the compressive strain is changed from −6% to −8%. And the BC 2 NH-II system can be changed into half-metal by applying the compressive strain between −6% and −7.5%. Our calculation results suggest a possible way to tune the electronic and magnetic properties by choosing the appropriate structural type and the external strain, which would have potential applications in spintronics and nanodevices. [ABSTRACT FROM AUTHOR]

Engineering fluorescent proteins to be the customized in vivo labels for monitoring cellular dynamic events is critical in biochemical and biomedical studies. The design and development of novel red fluorescent proteins is one of the most important fronts in this field due to their potential of imaging the entire organism. A recent fluorescent protein mutant eqFP650‐67‐HqAla with the 8‐hydroxyquinolin‐imidazolinone (HQI) chromophore has the plausible bathochromic shift of ~30 nm in its emission spectrum wavelength comparing to the parent fluorescent protein eqFP650. However, molecular mechanism of this significant shift remains somewhat obscure. In this study, we carefully benchmarked our computational methods and performed extensive calculations to investigate various structural components' effect on the chromophore's emission energy and decipher the molecular origin of the spectral shift. The influences of conjugation size, substituent group, substituent site as well as the number of substituents have been examined by elaborately designed chromophore derivatives. Accordingly, we proposed several chromophore mutants with dramatic bathochromic shift of up to ~60 nm in their emission spectra. We further evaluated their structural stability in the protein using molecular dynamics simulations. Present theoretical study connects the structural feature of chromophore derivatives in red fluorescent proteins with their splendid performances in shifting the emission frequency and offer the molecular insight. The computational protocol and successive examination procedure to extract the structural effect utilized herein can also be widely applied to other fluorescent proteins in general. © 2018 Wiley Periodicals, Inc. A theoretical study to connect the structural feature of chromophore derivatives in red fluorescent proteins is presented with their splendid performances in shifting the emission spectrum and provide the molecular insight to the spectral shift. Several chromophore mutants are designed with dramatic barochromic shift and validated their structural stability in the protein. The computational protocol and successive examination procedure to extract the structural effect utilized herein can also be widely applied to other fluorecence protein. [ABSTRACT FROM AUTHOR]

For tilted type-I Weyl semimetals, our theoretical study indicates that the Kubo conductivity parallel to cone tilt direction increases rapidly with the Fermi energy. Hence it deviates from its Boltzmann counterpart sizably even though the electronic wavelength is so short that the quantum interference is seemingly trivial. As a result, such a system shows huge anisotropy of the conductivity. By means of the diagrammatic expansion technique, we find that the absence of backscattering and the breakdown of the time reversal symmetry in tilted Weyl semimetals are two crucial factors which bring about the nontrivial inter-band contribution to the Kubo conductivity. Our findings indicate that Boltzmann theory fails to describe reasonably the electronic transport of a tilted Weyl cone, even in the case of weak scattering and short Fermi wavelength. Though in this regime such a semiclassical transport theory is believed to be valid according to conventional arguments. This situation should be paid attention. • We found a huge enhancement in diagonal conductivity caused by quantum corrections. • The huge anisotropy originates in the absence of backscattering and breakdown of TRS. • The interaction range of impurity potential affects the extent of anisotropy. [ABSTRACT FROM AUTHOR]

The presence of an extended line defect in graphene brings about some interesting electronic properties to such a truly two-dimensional (2D) carbon material, such as the energy-band engineering and valley filtering. By establishing an appropriate connection condition for the spinor wave function across the line defect, we find that the massless Dirac equation is still a valid theoretical model to describe low-energy electronic properties of the line defect embedded graphene structure. To check the validity of the wave-function connection condition, we take two kinds of line defect embedded graphene structures as examples to study the low-energy electronic states by solving the Dirac equation. First, for a line defect embedded zigzag-edged graphene nanoribbon, we obtain analytical results about the subband dispersion and eigenwave function, which coincide well with the numerical results from the tight-binding approach. Then, for a 2D graphene embedded with an extended line defect, we get an exact expression about the valley polarized electronic transmission probability, which demonstrates the simple result estimated previously in the zero-energy limit. More interestingly, our analytical result indicates that in such a 2D graphene structure a quasi-one-dimensional (ID) electronic state occurs along the line defect. And the electronic group velocity in this quasi-ID electronic state can be readily modulated by applying a strain field around the line defect. [ABSTRACT FROM AUTHOR]

As the newly member added to the graphene family, the high-buckled (HB) plumbene is a metallic two-dimensional(2D) material with the electronic structure characterized by the existence of some band edges in close proximity to the Fermi level. Hence in such a 2D material the electronic density of states (DOS) presents sharp peaks around the Fermi level. In this work, we perform first-principles calculations of the conventional superconducting critical temperature (T c) of HB plumbene. We find that the electron-phonon (e -ph) coupling strength which measures the electron mass enhancement is proportional to the DOS at the Fermi level. As a result, T c of HB plumbene has a sizable increase (from 5.29 K to 17.21 K) when the Fermi level is shifted to the nearby DOS peaks from its intrinsic position. For 2D materials, the adjustment of Fermi level can be readily realized by applying a gate voltage in a device structure of electronic transport, instead of a chemical carrier doping. Therefore, our study proposes a feasible way to tune T c of those 2D metallic materials such as HB plumbene which have some band edges or flat band around Fermi level. • The correction term for the strong-coupling case is considered. • The superconducting critical temperature can be tuned by altering the Fermi level. • SOC can enhance the superconducting critical temperature. • The superconducting critical temperature of HB plumbene has a sizable increase. [ABSTRACT FROM AUTHOR]

We present the phonon-limited electron mobility in planar T graphene and find that the mobility ∝ T − 5. 53 at low temperature T. With the increase of temperature, the power exponent 5.53 decreases towards 1. Excitingly, the room-temperature mobility of planar T graphene is 2. 78 × 1 0 6 cm 2 /Vs which is about 20.59 times as large as that of n -type graphene at the same carrier density. Different from graphene with longitudinal acoustic phonon dominating the mobility, an in-plane optical phonon mode contributes the most to the mobility of planar T graphene. • We obtain a very large room-temperature mobility (2.78 × 106 cm2/Vs) than that of monolayer graphene at the same carrier density, which makes it a promising candidate for future carbon material devices. • We observe a low-temperature behavior μ ∝ T-5.53 in the regime of partly screened electron–phonon interaction. Moreover, we predict a very high Bloch–Grüneisen temperature larger than the Debye one in planar T graphene. • Different from graphene with longitudinal acoustic phonon dominating the mobility, an in-plane optical phonon mode contributes the most to the mobility of planar T graphene. [ABSTRACT FROM AUTHOR]

We performed density functional theory calculations to investigate the electronic and magnetic properties of H-terminated zigzag BC 2 N nanoribbons (ZBC 2 NNRs) with the atoms arranged as B-C-N-C along zigzag lines. The ribbons can be classified into three groups according to the profiles of band structures and edge atoms: BN-BN, CC-CC and BN-CC. Among them, CC-CC and BN-CC ZBC 2 NNRs behave magnetic ground states. The results show that the CC-CC ZBC 2 NNR is an antiferromagnetic (AFM) semiconductor. Under the transverse electric field, the half-metallicity of 16-CC-CC ZBC 2 NNR can be achieved with electric field in the range of 0.2 ∼ 0.45 VÅ−1. Interestingly, the intrinsic half-metallicity exists in BN-CC ZBC 2 NNRs when the ribbon width is smaller than ∼29.2 Å. For larger ribbon width (∼33.5 Å), the system could be converted from ferromagnetic metal to half-metals at a very low critical field of E = 0.02 VÅ−1. Meanwhile, it is also shown that the I–V characteristic of BN-BN ZBC 2 NNRs shows a negative differential resistance (NDR) effect. These ample electronic and magnetic properties might open great opportunities for BC 2 N materials in spintronics and nanoscale device in the future. • Three groups of H-terminated ZBC 2 NNRs have been studied. • CC-CC ZBC 2 NNR is an antiferromagnetic semiconductor. • BN-CC ZBC 2 NNR is the intrinsic half-metallicity with width smaller than ∼29.2 Å. • Negative differential resistance can be observed in BN-BN ZBC 2 NNR device. [ABSTRACT FROM AUTHOR]

A π-electronic tight-binding (TB) model with, at most, three independent parameters is found to well fit the density functional theory results about the dispersions of the conduction and valence bands of α-, β-, γ- and (6,6,12)-graphyne. By means of such a toy model, the electron–hole symmetry in these graphynes is demonstrated. An explicit expression of the dispersion relation of α-graphyne is obtained. The position of the Dirac point on a particular Γ–M line in the Brillouin zone of β-graphyne is analytically determined. The absence of Dirac cones in γ-graphyne is intuitively explained. Based on these interesting results, it is believed that this TB model provides a simple but effective theoretical approach for further study of the electronic and transport properties of these typical graphynes. [ABSTRACT FROM AUTHOR]