We study analytically and numerically the nonlinear collective dynamics of quasi-one-dimensional spin-orbit coupled spin-1 Bose-Einstein condensates trapped in harmonic potential.The ground state of the system is dete...We study analytically and numerically the nonlinear collective dynamics of quasi-one-dimensional spin-orbit coupled spin-1 Bose-Einstein condensates trapped in harmonic potential.The ground state of the system is determined by minimizing the Lagrange density,and the coupled equations of motions for the center-of-mass coordinate of the condensate and its width are derived.Then,two low energy excitation modes in breathing dynamics and dipole dynamics are obtained analytically,and the mechanism of exciting the anharmonic collective dynamics is revealed explicitly.The coupling among spin-orbit coupling,Raman coupling and spin-dependent interaction results in multiple external collective modes,which leads to the anharmonic collective dynamics.The cooperative effect of spin momentum locking and spin-dependent interaction results in coupling of dipolar and breathing dynamics,which strongly depends on spin-dependent interaction and behaves distinct characters in different phases.Interestingly,in the absence of spin-dependent interaction,the breathing dynamics is decoupled from spin dynamics and the breathing dynamics is harmonic.Our results provide theoretical evidence for deep understanding of the ground sate phase transition and the nonlinear collective dynamics of the system.展开更多
Based on the Bogoliubov-de Gennes equation and the extended McMillan’s Green’s function formalism,we study theoretically the Josephson effect between two d-wave superconductors bridged by a ballistic two-dimensional...Based on the Bogoliubov-de Gennes equation and the extended McMillan’s Green’s function formalism,we study theoretically the Josephson effect between two d-wave superconductors bridged by a ballistic two-dimensional electron gas with both Rashba spin-orbit coupling and Zeeman splitting.We show that due to the interplay of Rashba spin-orbit coupling and Zeeman splitting and d-wave pairing,the current-phase relation in such a heterostructure may exhibit a series of novel features and can change significantly as some relevant parameters are tuned.In particular,anomalous Josephson current may occur at zero phase bias under various different situations if both time reversal symmetry and inversion symmetry of the system are simultaneously broken,which can be realized by tuning some relevant parameters of the system,including the relative orientations and the strengths of the Zeeman field and the spin-orbit field in the bridge region,the relative orientations of the a axes in two superconductor leads,or the relative orientations between the Zeeman field in the bridge region and the a axes in the superconductor leads.We show that both the magnitude and the direction of the anomalous Josephson current may depend sensitively on these relevant parameters.展开更多
Current induced spin-orbit torque(SOT)switching of magnetization is a promising technology for nonvolatile spintronic memory and logic applications.In this work,we systematically investigated the effect of Ta thicknes...Current induced spin-orbit torque(SOT)switching of magnetization is a promising technology for nonvolatile spintronic memory and logic applications.In this work,we systematically investigated the effect of Ta thickness on the magnetic properties,field-free switching and SOT efficiency in a ferromagnetically coupled Co/Ta/Co Fe B trilayer with perpendicular magnetic anisotropy.We found that both the anisotropy field and coercivity increase with increasing Ta thickness from0.15 nm to 0.4 nm.With further increase of Ta thickness to 0.5 nm,two-step switching is observed,indicating that the two magnetic layers are magnetically decoupled.Measurements of pulse-current induced magnetization switching and harmonic Hall voltages show that the critical switching current density increases while the field-free switching ratio and SOT efficiency decrease with increasing Ta thickness.Both the enhanced spin memory loss and reduced interlayer exchange coupling might be responsible for theβ_(DL)decrease as the Ta spacer thickness increases.The studied structure with the incorporation of a Co Fe B layer is able to realize field-free switching in the strong ferromagnetic coupling region,which may contribute to the further development of magnetic tunnel junctions for better memory applications.展开更多
We have investigated theoretically the field-driven electron-transport through a double-quantum-well semiconductor-heterostructure with spin-orbit coupling. The numerical results demonstrate that the transmission spec...We have investigated theoretically the field-driven electron-transport through a double-quantum-well semiconductor-heterostructure with spin-orbit coupling. The numerical results demonstrate that the transmission spectra are divided into two sets due to the bound-state level-splitting and each set contains two asymmetric resonance peaks which may be selectively suppressed by changing the difference in phase between two driving fields. When the phase difference changes from 0 to π, the dip of asymmetric resonance shifts from one side of resonance peak to the other side and the asymmetric Fano resonance degenerates into the symmetric Breit-Wigner resonance at a critical value of phase difference. Within a given range of incident electron energy, the spin polarization of transmission current is completely governed by the phase difference which may be used to realize the tunable spin filtering.展开更多
We have studied the spin-dependent electron transmission through a quantum well driven by both dipole-type and homogeneous oscillating fields. The numerical evaluations show that Dresselhaus spin-orbit coupling induce...We have studied the spin-dependent electron transmission through a quantum well driven by both dipole-type and homogeneous oscillating fields. The numerical evaluations show that Dresselhaus spin-orbit coupling induces the splitting of asymmetric Fano-type resonance peaks in the conductivity, in which the dipole modulation and the homogeneous modulation are equivalent. Therefore, we predict that the dipole-type oscillation, which is more practical in the experimental setup, can be used to realize the tunable spin filters by adjusting the field oscillation-frequency and the amplitude as well.展开更多
The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin-orbit coupling we...The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin-orbit coupling were investigated theoretically. Based on a unified semiclassical theoretical approach, it is shown that the total anomalous Hall conductivity can be expressed as the sum of three distinct contributions in the presence of these competing spin-orbit interactions, namely an intrinsic contribution determined by the Berry curvature in the momentum space, an extrinsic contribution determined by the modified Bloch band group velocity and an extrinsic contribution determined by spin-orbit-dependent impurity scattering. The characteristics of these competing contributions are discussed in detail in the paper.展开更多
Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling. The heat generated by the spin current is calculated. With the...Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling. The heat generated by the spin current is calculated. With the increase of the width of the quantum wire, the spin current and the heat generated both exhibit period oscillations with equal amplitudes. When the quantum-channel number is doubled, the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2. For the spin current js,xy, the amplitude increases with the decrease of the quantum channel; while the amplitude of the spin current js,yx remains the same. Therefore we conclude that the effect of the quantum-channel number on the spin current js,xy is greater than that on the spin current js,yx. The strength of the Rashba spin-orbit coupling is tunable by the gate voltage, and the gate voltage can be varied experimentally, which implies a new method of detecting the. spin current. In addition, we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels. All these characteristics of the spin current will be very important for detecting and controlling the spin current, and especially for designing new spintronic devices in the future.展开更多
Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling (SOC) are investigated analytically using quantum networks and the transport matrix metLod. The results show th...Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling (SOC) are investigated analytically using quantum networks and the transport matrix metLod. The results show that conduc- tances remain at exactly the same values when the output leads are located at axisymmetric positions. However, for the nonaxisymmetrical case, there is a phase difference between the upper and lower arm, which leads to zero conductances appearing periodically. An isotropy of the conductance is destroyed by the Rashba SOC effect in the axisymmetric case. In addition, the position of zero conductance is regulated with the strength of the Rashba SOC.展开更多
We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction (RSOI), coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two...We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction (RSOI), coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two ferromagnetic leads and two quantum dots form a ring threaded by Aharonov-Bohm (AB) flux. This device possesses normal quasiparticle transmission between the two ferromagnetic leads, and normal and crossed Andreev reflections providing conductive holes. For the appropriate spin polarization of the ferromagnetic leads, RSOI and AB flux, the pure spin-up (or spin-down) current without net charge current in the right lead, which is due to the equal numbers of electrons and holes with the same spin-polarization moving along the same direction, can be obtained by adjusting the gate voltage, which may be used in practice as a pure spin-current injector.展开更多
Using a transfer matrix method, we investigate spin transport through a chain of polygonal rings with Dresselhaus spin-orbit coupling(DSOC). The spin conductance is dependent on the number of sides in the polygons. ...Using a transfer matrix method, we investigate spin transport through a chain of polygonal rings with Dresselhaus spin-orbit coupling(DSOC). The spin conductance is dependent on the number of sides in the polygons. When DSOC is considered in a chain which also has Rashba spin-orbit coupling(RSOC) of the same magnitude, the total conductance is the same as that for the same chain with no SOC. However, when the two types of SOC have different values, there results a unique anisotropic conductance.展开更多
An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI+Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states ...An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI+Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states of MgH are derived. Then the associated spectroscopic parameters are determined and found to be in good accordance with the available experimental results. The permanent dipole moments (PDMs) and the spin-orbit (SO) matrix elements of A-S states are computed. The results show that the abrupt changes of PDMs and SO matrix elements are attributed to the variations of electronic configurations at the avoided crossing point. The SOC effect leads to the five A-S states split into ten Ω states and results in the double potential well of (2)1//2 state. Finally, the transition properties from the (2)1//2, (1)3//2 and (3)1//2 states to the ground state X2∑+1//2 transitions are obtained, including the transition dipole moments, Franck-Condon factors and radiative lifetimes.展开更多
Valley filter is a promising device for producing valley polarized current in graphene-like two-dimensional honeycomb lattice materials.The relatively large spin-orbit coupling in silicene contributes to remarkable qu...Valley filter is a promising device for producing valley polarized current in graphene-like two-dimensional honeycomb lattice materials.The relatively large spin-orbit coupling in silicene contributes to remarkable quantum spin Hall effect,which leads to distinctive valley-dependent transport properties compared with intrinsic graphene.In this paper,quantized conductance and valley polarization in silicene nanoconstrictions are theoretically investigated in quantum spin-Hall insulator phase.Nearly perfect valley filter effect is found by aligning the gate voltage in the central constriction region.However,the valley polarization plateaus are shifted with the increase of spin-orbit coupling strength,accompanied by smooth variation of polarization reversal.Our findings provide new strategies to control the valley polarization in valleytronic devices.展开更多
We investigate the vortex structures excited by Ioffe-Pritchard magnetic field and Dresselhaus-type spin-orbit coupling in F=2 ferromagnetic Bose-Einstein condensates.In the weakly interatomic interacting regime,an ex...We investigate the vortex structures excited by Ioffe-Pritchard magnetic field and Dresselhaus-type spin-orbit coupling in F=2 ferromagnetic Bose-Einstein condensates.In the weakly interatomic interacting regime,an external magnetic field can generate a polar-core vortex in which the canonical particle current is zero.With the combined effect of spin-orbit coupling and magnetic field,the ground state experiences a transition from polar-core vortex to Mermin-Ho vortex,in which the canonical particle current is anticlockwise.For fixed spin-orbit coupling strengths,the evolution of phase winding,magnetization,and degree of phase separation with magnetic field are studied.Additionally,with further increasing spin-orbit coupling strength,the condensate exhibits symmetrical density domains separated by radial vortex arrays.Our work paves the way to explore exotic topological excitations in high-spin systems.展开更多
Topological superfluid state is different from the normal superfluid one due to the excitation energy gap on the boundary.How to obtain the topological superfluid state by using spin-orbit coupling to control the s-wa...Topological superfluid state is different from the normal superfluid one due to the excitation energy gap on the boundary.How to obtain the topological superfluid state by using spin-orbit coupling to control the s-waves paired mass-imbalanced Fermi gas is a recent novel topic.In this paper,we study the topological superfluid phase diagram of two-dimensional mass-imbalanced Fermi gas with Rashba spin-orbit coupling at zero temperature.We find that due to the competition among mass imbalance,pairing interaction and spin-orbit coupling,there is a double-well structure in the thermodynamic potential,which affects the properties of the ground state of the system.We comprehensively give the phase diagrams of the system on the plane of spin-orbit coupling and chemical potential,and the phase diagrams on the plane of the reduced mass ratio and two-body binding energy.This study not only points out the stable region of topolog-ical superfluid state of mass-imbalanced Fermi gas,but also provides a detailed theoretical basis for better observation of topological superfluid state in experiments.展开更多
We investigated the effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors.A Lorentz-type magnetoresistance is obtained from spin-orbit coupling-dependent spin precession under the co...We investigated the effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors.A Lorentz-type magnetoresistance is obtained from spin-orbit coupling-dependent spin precession under the condition of a space-charge-limited current.The magnetoresistance depends on the initial spin orientation of the electron with respect to the hole in electron-hole pairs,and the increasing spin-orbit coupling slows down the change in magnetoresistance with magnetic field.The field dependence,the sign and the saturation value of the magnetoresistance are composite effects of recombination and dissociation rate constants of singlet and triplet electron-hole pairs.The simulated magnetoresistance shows good consistency with the experimental results.展开更多
We investigate theoretically the spin-dependent electron transport in a straight waveguide with Rashba spin-orbit coupling (SOC) under the irradiation of a transversely polarized electromagnetic (EM) field. Spin-d...We investigate theoretically the spin-dependent electron transport in a straight waveguide with Rashba spin-orbit coupling (SOC) under the irradiation of a transversely polarized electromagnetic (EM) field. Spin-dependent electron conductance and spin polarization are calculated as functions of the emitting energy of electrons or the strength of the EM field by adopting the mode matching approach. It is shown that the spin polarization can be manipulated by external parameters when the strength of Rashba SOC is strong. Furthermore, a sharp step structure is found to exist in the total electron conductance. These results can he understood by the nontrivial Rashba subbands intermixing and the electron intersubband transition when a finite-range transversely polarized EM field irradiates a straight waveguide.展开更多
Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is pr...Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is predominately plagued by its severe capacity degradation,mainly associated with the innate Jahn-Teller effect.Herein,single-crystalline LiMn_(2)O_(4)with Eu^(3+) doping is rationally designed to mitigate the detrimental Jahn-Teller distortion by tuning the chemical environment of MnO_(6) octahedra and accommodating localized electron,based on the unique aspheric flexible 4f electron orbit of rare-earth metal ions.Notably,the stretching of MnO_(6) octahedron stemmed from the Jahn-Teller effect in Eu-doped LiMn_(2)O_(4)is effectively suppressed,confirmed by theoretical calculation.Meanwhile,the structural stability of the material has been significantly enhanced due to the robust Mn–O band coherency and weakened phase transition,proved by synchrotron radiation absorption spectrum and operando X-ray diffraction.The corresponding active cathode manifests superior long-cycle stability after 300 loops at 2C and displays only a 0.011%capacity drop per cycle even at 5C.Given this,this modification tactic sheds new light on achieving superior long-cycle performances by suppressing distortion in various cathode materials.展开更多
We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling. The splitting of the asymmetric Fano-type resonance peaks du...We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling. The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin-orbit coupling is found to be highly sensitive to the direction of the incident electron. The splitting of the Fano-type resonance induces the spin-polarization dependent electron current. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents.展开更多
We present theoretical calculations of spin transport in spin filtering magnetic tunnelling junctions based on the Landauer Biittiker formalism and taking into account the spin-orbit coupling (SOC). It is shown that...We present theoretical calculations of spin transport in spin filtering magnetic tunnelling junctions based on the Landauer Biittiker formalism and taking into account the spin-orbit coupling (SOC). It is shown that spin-flip scattering induced by SOC is stronger in parallel alignment of magnetization of the ferromegnet barrier (FB) and the ferromagnetic electrode than that in antiparallel case. The increase of negative tunnelling magnetoresistance with bias is in agreement with recent experimental observation.展开更多
We consider two-dimensional spinor F=1 Bose-Einstein condensates in two types of radially-periodic potentials with spin-orbit coupling,i.e.,spin-independent and spin-dependent radially-periodic potentials.For the Bose...We consider two-dimensional spinor F=1 Bose-Einstein condensates in two types of radially-periodic potentials with spin-orbit coupling,i.e.,spin-independent and spin-dependent radially-periodic potentials.For the Bose-Einstein condensates in a spin-independent radially-periodic potential,the density of each component exhibits the periodic density modulation along the azimuthal direction,which realizes the necklacelike state in the ferromagnetic Bose-Einstein condensates.As the spin-exchange interaction increases,the necklacelike state gradually transition to the plane wave phase for the antiferromagnetic Bose-Einstein condensates with larger spin-orbit coupling.The competition of the spin-dependent radially-periodic potential,spin-orbit coupling,and spin-exchange interaction gives rise to the exotic ground-state phases when the Bose-Einstein condensates in a spin-dependent radially-periodic potential.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12164042,12264045,11764039,11475027,11865014,12104374,and 11847304)the Natural Science Foundation of Gansu Province(Grant Nos.17JR5RA076 and 20JR5RA526)+2 种基金the Scientific Research Project of Gansu Higher Education(Grant No.2016A-005)the Innovation Capability Enhancement Project of Gansu Higher Education(Grant Nos.2020A-146 and 2019A-014)the Creation of Science and Technology of Northwest Normal University(Grant No.NWNU-LKQN-18-33)。
文摘We study analytically and numerically the nonlinear collective dynamics of quasi-one-dimensional spin-orbit coupled spin-1 Bose-Einstein condensates trapped in harmonic potential.The ground state of the system is determined by minimizing the Lagrange density,and the coupled equations of motions for the center-of-mass coordinate of the condensate and its width are derived.Then,two low energy excitation modes in breathing dynamics and dipole dynamics are obtained analytically,and the mechanism of exciting the anharmonic collective dynamics is revealed explicitly.The coupling among spin-orbit coupling,Raman coupling and spin-dependent interaction results in multiple external collective modes,which leads to the anharmonic collective dynamics.The cooperative effect of spin momentum locking and spin-dependent interaction results in coupling of dipolar and breathing dynamics,which strongly depends on spin-dependent interaction and behaves distinct characters in different phases.Interestingly,in the absence of spin-dependent interaction,the breathing dynamics is decoupled from spin dynamics and the breathing dynamics is harmonic.Our results provide theoretical evidence for deep understanding of the ground sate phase transition and the nonlinear collective dynamics of the system.
文摘Based on the Bogoliubov-de Gennes equation and the extended McMillan’s Green’s function formalism,we study theoretically the Josephson effect between two d-wave superconductors bridged by a ballistic two-dimensional electron gas with both Rashba spin-orbit coupling and Zeeman splitting.We show that due to the interplay of Rashba spin-orbit coupling and Zeeman splitting and d-wave pairing,the current-phase relation in such a heterostructure may exhibit a series of novel features and can change significantly as some relevant parameters are tuned.In particular,anomalous Josephson current may occur at zero phase bias under various different situations if both time reversal symmetry and inversion symmetry of the system are simultaneously broken,which can be realized by tuning some relevant parameters of the system,including the relative orientations and the strengths of the Zeeman field and the spin-orbit field in the bridge region,the relative orientations of the a axes in two superconductor leads,or the relative orientations between the Zeeman field in the bridge region and the a axes in the superconductor leads.We show that both the magnitude and the direction of the anomalous Josephson current may depend sensitively on these relevant parameters.
基金Project supported by the‘Pioneer’and‘Leading Goose’Research and Development Program of Zhejiang Province,China(Grant No.2022C01053)the National Natural Science Foundation of China(Grant Nos.11874135,12104119+2 种基金12004090)Key Research and Development Program of Zhejiang Province,China(Grant No.2021C01039)Natural Science Foundation of Zhejiang Province,China(Grant Nos.LQ20F040005 and LQ21A050001)。
文摘Current induced spin-orbit torque(SOT)switching of magnetization is a promising technology for nonvolatile spintronic memory and logic applications.In this work,we systematically investigated the effect of Ta thickness on the magnetic properties,field-free switching and SOT efficiency in a ferromagnetically coupled Co/Ta/Co Fe B trilayer with perpendicular magnetic anisotropy.We found that both the anisotropy field and coercivity increase with increasing Ta thickness from0.15 nm to 0.4 nm.With further increase of Ta thickness to 0.5 nm,two-step switching is observed,indicating that the two magnetic layers are magnetically decoupled.Measurements of pulse-current induced magnetization switching and harmonic Hall voltages show that the critical switching current density increases while the field-free switching ratio and SOT efficiency decrease with increasing Ta thickness.Both the enhanced spin memory loss and reduced interlayer exchange coupling might be responsible for theβ_(DL)decrease as the Ta spacer thickness increases.The studied structure with the incorporation of a Co Fe B layer is able to realize field-free switching in the strong ferromagnetic coupling region,which may contribute to the further development of magnetic tunnel junctions for better memory applications.
基金supported by the National Natural Science Foundation of China (Grant Nos 10475053,10775091 and 10774094)the Shanxi Natural Science Foundation,China (Grant No 20051002)
文摘We have investigated theoretically the field-driven electron-transport through a double-quantum-well semiconductor-heterostructure with spin-orbit coupling. The numerical results demonstrate that the transmission spectra are divided into two sets due to the bound-state level-splitting and each set contains two asymmetric resonance peaks which may be selectively suppressed by changing the difference in phase between two driving fields. When the phase difference changes from 0 to π, the dip of asymmetric resonance shifts from one side of resonance peak to the other side and the asymmetric Fano resonance degenerates into the symmetric Breit-Wigner resonance at a critical value of phase difference. Within a given range of incident electron energy, the spin polarization of transmission current is completely governed by the phase difference which may be used to realize the tunable spin filtering.
基金supported by the National Natural Science Foundation of China (Grant Nos 10475053,10775091 and 10774094)the Shanxi Natural Science Foundation of China (Grant No 20051002)
文摘We have studied the spin-dependent electron transmission through a quantum well driven by both dipole-type and homogeneous oscillating fields. The numerical evaluations show that Dresselhaus spin-orbit coupling induces the splitting of asymmetric Fano-type resonance peaks in the conductivity, in which the dipole modulation and the homogeneous modulation are equivalent. Therefore, we predict that the dipole-type oscillation, which is more practical in the experimental setup, can be used to realize the tunable spin filters by adjusting the field oscillation-frequency and the amplitude as well.
基金supported by the National Natural Science Foundation of China (Grant No.10874049)
文摘The various competing contributions to the anomalous Hall effect in spin-polarized two-dimensional electron gases in the presence of both intrinsic, extrinsic and external electric-field induced spin-orbit coupling were investigated theoretically. Based on a unified semiclassical theoretical approach, it is shown that the total anomalous Hall conductivity can be expressed as the sum of three distinct contributions in the presence of these competing spin-orbit interactions, namely an intrinsic contribution determined by the Berry curvature in the momentum space, an extrinsic contribution determined by the modified Bloch band group velocity and an extrinsic contribution determined by spin-orbit-dependent impurity scattering. The characteristics of these competing contributions are discussed in detail in the paper.
文摘Using the perturbation method, we theoretically study the spin current and its heat effect in a multichannel quantum wire with Rashba spin-orbit coupling. The heat generated by the spin current is calculated. With the increase of the width of the quantum wire, the spin current and the heat generated both exhibit period oscillations with equal amplitudes. When the quantum-channel number is doubled, the oscillation periods of the spin current and of the heat generated both decrease by a factor of 2. For the spin current js,xy, the amplitude increases with the decrease of the quantum channel; while the amplitude of the spin current js,yx remains the same. Therefore we conclude that the effect of the quantum-channel number on the spin current js,xy is greater than that on the spin current js,yx. The strength of the Rashba spin-orbit coupling is tunable by the gate voltage, and the gate voltage can be varied experimentally, which implies a new method of detecting the. spin current. In addition, we can control the amplitude and the oscillation period of the spin current by controlling the number of the quantum channels. All these characteristics of the spin current will be very important for detecting and controlling the spin current, and especially for designing new spintronic devices in the future.
基金Project supported by the National Natural Science Foundation of China(Grant No.61176089)Hebei Provincial Natural Science Foundation,China(Grant No.A2011205092)
文摘Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling (SOC) are investigated analytically using quantum networks and the transport matrix metLod. The results show that conduc- tances remain at exactly the same values when the output leads are located at axisymmetric positions. However, for the nonaxisymmetrical case, there is a phase difference between the upper and lower arm, which leads to zero conductances appearing periodically. An isotropy of the conductance is destroyed by the Rashba SOC effect in the axisymmetric case. In addition, the position of zero conductance is regulated with the strength of the Rashba SOC.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10775091,10774094,10974124,and 11047172)the Excellent Youth and Midlife Scientist Scientific Research Encouragement Foundation of Shandong Province,China(Grant No. BS2010DS006)the Doctor Research Startup Foundation of Linyi University,China (Grant No. BS201023)
文摘We propose a four-terminal device consisting of two parallel quantum dots with Rashba spin-orbit interaction (RSOI), coupled to two side superconductor leads and two common ferromagnetic leads, respectively. The two ferromagnetic leads and two quantum dots form a ring threaded by Aharonov-Bohm (AB) flux. This device possesses normal quasiparticle transmission between the two ferromagnetic leads, and normal and crossed Andreev reflections providing conductive holes. For the appropriate spin polarization of the ferromagnetic leads, RSOI and AB flux, the pure spin-up (or spin-down) current without net charge current in the right lead, which is due to the equal numbers of electrons and holes with the same spin-polarization moving along the same direction, can be obtained by adjusting the gate voltage, which may be used in practice as a pure spin-current injector.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61176089 and 11504083)the Foundation of Shijiazhuang University,China(Grant No.XJPT002)
文摘Using a transfer matrix method, we investigate spin transport through a chain of polygonal rings with Dresselhaus spin-orbit coupling(DSOC). The spin conductance is dependent on the number of sides in the polygons. When DSOC is considered in a chain which also has Rashba spin-orbit coupling(RSOC) of the same magnitude, the total conductance is the same as that for the same chain with no SOC. However, when the two types of SOC have different values, there results a unique anisotropic conductance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11564019,11574114,11147158,91221301 and 11264020the Natural Science Foundation of Jilin Province under Grant No 20150101003JC
文摘An accurate theoretical study on the MgH radical is reported by adopting the high-level relativistic MRCI+Q method with a quintuple-zeta quality basis set. The reliable potential energy curves of the five A-S states of MgH are derived. Then the associated spectroscopic parameters are determined and found to be in good accordance with the available experimental results. The permanent dipole moments (PDMs) and the spin-orbit (SO) matrix elements of A-S states are computed. The results show that the abrupt changes of PDMs and SO matrix elements are attributed to the variations of electronic configurations at the avoided crossing point. The SOC effect leads to the five A-S states split into ten Ω states and results in the double potential well of (2)1//2 state. Finally, the transition properties from the (2)1//2, (1)3//2 and (3)1//2 states to the ground state X2∑+1//2 transitions are obtained, including the transition dipole moments, Franck-Condon factors and radiative lifetimes.
基金the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ17A040001)the National Natural Science Foundation of China(Grant Nos.61874078,11647046,and 61904125)+1 种基金the National Key Research and Development Program of China(Grant No.2018YFB2202100)the Science and Technology Planning Project of Wenzhou City(Grant No.G20180012).
文摘Valley filter is a promising device for producing valley polarized current in graphene-like two-dimensional honeycomb lattice materials.The relatively large spin-orbit coupling in silicene contributes to remarkable quantum spin Hall effect,which leads to distinctive valley-dependent transport properties compared with intrinsic graphene.In this paper,quantized conductance and valley polarization in silicene nanoconstrictions are theoretically investigated in quantum spin-Hall insulator phase.Nearly perfect valley filter effect is found by aligning the gate voltage in the central constriction region.However,the valley polarization plateaus are shifted with the increase of spin-orbit coupling strength,accompanied by smooth variation of polarization reversal.Our findings provide new strategies to control the valley polarization in valleytronic devices.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0301500)the National Natural Science Foundation of China(Grant Nos.61835013 and 11971067)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB01020300 and XDB21030300)Beijing Natural Science Foundation,China(Grant No.1182009)Beijing Great Wall Talents Cultivation Program,China(Grant No.CIT&TCD20180325)。
文摘We investigate the vortex structures excited by Ioffe-Pritchard magnetic field and Dresselhaus-type spin-orbit coupling in F=2 ferromagnetic Bose-Einstein condensates.In the weakly interatomic interacting regime,an external magnetic field can generate a polar-core vortex in which the canonical particle current is zero.With the combined effect of spin-orbit coupling and magnetic field,the ground state experiences a transition from polar-core vortex to Mermin-Ho vortex,in which the canonical particle current is anticlockwise.For fixed spin-orbit coupling strengths,the evolution of phase winding,magnetization,and degree of phase separation with magnetic field are studied.Additionally,with further increasing spin-orbit coupling strength,the condensate exhibits symmetrical density domains separated by radial vortex arrays.Our work paves the way to explore exotic topological excitations in high-spin systems.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11875149, 11874127, 52061014, and 61565007)the Youth Jing-gang Scholars Program of Jiangxi Province, Chinathe Program of Qing-jiang Excellent Young Talents, Jiangxi University of Science and Technology
文摘Topological superfluid state is different from the normal superfluid one due to the excitation energy gap on the boundary.How to obtain the topological superfluid state by using spin-orbit coupling to control the s-waves paired mass-imbalanced Fermi gas is a recent novel topic.In this paper,we study the topological superfluid phase diagram of two-dimensional mass-imbalanced Fermi gas with Rashba spin-orbit coupling at zero temperature.We find that due to the competition among mass imbalance,pairing interaction and spin-orbit coupling,there is a double-well structure in the thermodynamic potential,which affects the properties of the ground state of the system.We comprehensively give the phase diagrams of the system on the plane of spin-orbit coupling and chemical potential,and the phase diagrams on the plane of the reduced mass ratio and two-body binding energy.This study not only points out the stable region of topolog-ical superfluid state of mass-imbalanced Fermi gas,but also provides a detailed theoretical basis for better observation of topological superfluid state in experiments.
基金Project supported by the National Natural Science Foundation of China (Grant No. 11005070)and the Research Planning Project of Ministry of Housing and Urban-Rural Development,China (Grant No. 2010-K4-15)
文摘We investigated the effect of spin-orbit coupling on magnetoresistance in nonmagnetic organic semiconductors.A Lorentz-type magnetoresistance is obtained from spin-orbit coupling-dependent spin precession under the condition of a space-charge-limited current.The magnetoresistance depends on the initial spin orientation of the electron with respect to the hole in electron-hole pairs,and the increasing spin-orbit coupling slows down the change in magnetoresistance with magnetic field.The field dependence,the sign and the saturation value of the magnetoresistance are composite effects of recombination and dissociation rate constants of singlet and triplet electron-hole pairs.The simulated magnetoresistance shows good consistency with the experimental results.
基金Project supported by the National Natural Science Foundation of China (Grant No 10774112)by the Science Foundation for Young Scientists of Jiangxi Agricultural University,China (Grant No 2219)
文摘We investigate theoretically the spin-dependent electron transport in a straight waveguide with Rashba spin-orbit coupling (SOC) under the irradiation of a transversely polarized electromagnetic (EM) field. Spin-dependent electron conductance and spin polarization are calculated as functions of the emitting energy of electrons or the strength of the EM field by adopting the mode matching approach. It is shown that the spin polarization can be manipulated by external parameters when the strength of Rashba SOC is strong. Furthermore, a sharp step structure is found to exist in the total electron conductance. These results can he understood by the nontrivial Rashba subbands intermixing and the electron intersubband transition when a finite-range transversely polarized EM field irradiates a straight waveguide.
基金financially supported by the National Natural Science Foundation of China(U21A20284)the National Key Research and Development Program of China(2019YFC1907805)the Fundamental Research Funds for the Central Universities of Central South University(2021zzts0072)。
文摘Spinel LiMn_(2)O_(4)is recognized as one of the most competitive cathode candidates for lithium-ion batteries ascribed to environmentally benign and rich sources.However,the wholesale application of LiMn_(2)O_(4)is predominately plagued by its severe capacity degradation,mainly associated with the innate Jahn-Teller effect.Herein,single-crystalline LiMn_(2)O_(4)with Eu^(3+) doping is rationally designed to mitigate the detrimental Jahn-Teller distortion by tuning the chemical environment of MnO_(6) octahedra and accommodating localized electron,based on the unique aspheric flexible 4f electron orbit of rare-earth metal ions.Notably,the stretching of MnO_(6) octahedron stemmed from the Jahn-Teller effect in Eu-doped LiMn_(2)O_(4)is effectively suppressed,confirmed by theoretical calculation.Meanwhile,the structural stability of the material has been significantly enhanced due to the robust Mn–O band coherency and weakened phase transition,proved by synchrotron radiation absorption spectrum and operando X-ray diffraction.The corresponding active cathode manifests superior long-cycle stability after 300 loops at 2C and displays only a 0.011%capacity drop per cycle even at 5C.Given this,this modification tactic sheds new light on achieving superior long-cycle performances by suppressing distortion in various cathode materials.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11147173 and 61106052)the Zhejiang Education Department, China (Grant No. Y201018926 and Y200908466)+2 种基金the Basic Research Foundation of Jilin University,China (Grant No. 93K172011K02)the Basic Research Foundation of Zhejiang Ocean University, the Nature Science Foundation of Zhejiang Province, China (Grant No. 1047172)the Open Foundation from Ocean Fishery Science and Technology in the Most Important Subjects of Zhejiang, China(No. 20110105)
文摘We have investigated theoretically the field-driven electron transport through a single-quantum-well semiconductor heterostructure with spin-orbit coupling. The splitting of the asymmetric Fano-type resonance peaks due to the Dresselhaus spin-orbit coupling is found to be highly sensitive to the direction of the incident electron. The splitting of the Fano-type resonance induces the spin-polarization dependent electron current. The location and the line shape of the Fano-type resonance can be controlled by adjusting the energy and the direction of the incident electron, the oscillation frequency, and the amplitude of the external field. These interesting features may be used to devise tunable spin filters and realize pure spin transmission currents.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10564004)Korea Research Foundation(Grant No. KRF-2005-070-C00065)
文摘We present theoretical calculations of spin transport in spin filtering magnetic tunnelling junctions based on the Landauer Biittiker formalism and taking into account the spin-orbit coupling (SOC). It is shown that spin-flip scattering induced by SOC is stronger in parallel alignment of magnetization of the ferromegnet barrier (FB) and the ferromagnetic electrode than that in antiparallel case. The increase of negative tunnelling magnetoresistance with bias is in agreement with recent experimental observation.
基金supported by the National Natural Science of China(Grant Nos.11904242 and 12004264)the Natural Science Foundation of Hebei Province,China(Grant Nos.A2019210280 and A2019210124)。
文摘We consider two-dimensional spinor F=1 Bose-Einstein condensates in two types of radially-periodic potentials with spin-orbit coupling,i.e.,spin-independent and spin-dependent radially-periodic potentials.For the Bose-Einstein condensates in a spin-independent radially-periodic potential,the density of each component exhibits the periodic density modulation along the azimuthal direction,which realizes the necklacelike state in the ferromagnetic Bose-Einstein condensates.As the spin-exchange interaction increases,the necklacelike state gradually transition to the plane wave phase for the antiferromagnetic Bose-Einstein condensates with larger spin-orbit coupling.The competition of the spin-dependent radially-periodic potential,spin-orbit coupling,and spin-exchange interaction gives rise to the exotic ground-state phases when the Bose-Einstein condensates in a spin-dependent radially-periodic potential.