Topological zero-line modes(ZLMs) with spin and valley degrees of freedom give rise to spin, valley and spinvalley transport, which support a platform for exploring quantum transport physics and potential applications...Topological zero-line modes(ZLMs) with spin and valley degrees of freedom give rise to spin, valley and spinvalley transport, which support a platform for exploring quantum transport physics and potential applications in spintronic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current due to the ZLMs in a three-terminal system. We show that with certain combinations of ZLMs, the incident charge current along the interface between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals. As a result, fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. The mechanism of these splitters is attributed to the cooperative effects of the distribution of the ZLMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch. Interestingly, half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam splitter.Furthermore, the results indicate that these splitters can be applicable to graphene, silicene, germanene and stanene due to their robustness against the spin–orbit coupling. Our findings offer a new way to understand the transport mechanism and investigate the promising applications of ZLMs.展开更多
We systematically studied the influence of magnetic field on zero-line modes (ZLMs) in graphene and demonstrated the physical origin of their enhanced robustness by employing noneqnilibrium Green's functions and t...We systematically studied the influence of magnetic field on zero-line modes (ZLMs) in graphene and demonstrated the physical origin of their enhanced robustness by employing noneqnilibrium Green's functions and the Landauer Biittiker formula. We found that a perpendicular magnetic field can separate the wavefunctions of the counter-propagating kink states into opposite directions. Specifically, the separation vanishes at the charge neutrality point and increases as the Fermi level deviates from the charge neutrality point and can reach a magnitude comparable to the wavefunction spread at a moderate field strength. Such spatial separation of oppositely propagating ZLMs effectively suppresses backseattering and is more significant under zigzag boundary condition thail under armchair boundary condition. Moreover, the presence of magnetic field enlarges the bulk gap and suppresses the bound states, thereby further reducing the scattering. These mechanisms effectively increase the mean free paths of the ZLMs to approximately 1 |ini in the presence of a disorder.展开更多
We study theoretically the construction of topological conducting domain walls with a finite width between AB/BA stacking regions via finite element method in bilayer graphene systems with tunable commensurate twistin...We study theoretically the construction of topological conducting domain walls with a finite width between AB/BA stacking regions via finite element method in bilayer graphene systems with tunable commensurate twisting angles.We find that the smaller is the twisting angle,the more significant the lattice reconstruction would be,so that sharper domain boundaries declare their existence.We subsequently study the quantum transport properties of topological zero-line modes which can exist because of the said domain boundaries via Green’s function method and Landauer–Büttiker formalism,and find that in scattering regions with triintersectional conducting channels,topological zero-line modes both exhibit robust behavior exemplified as the saturated total transmission Gtot≈2e_(2)/h and obey a specific pseudospin-conserving current partition law among the branch transport channels.The former property is unaffected by Aharonov–Bohm effect due to a weak perpendicular magnetic field,but the latter is not.Results from our genuine bilayer hexagonal system suggest a twisting angle aroundθ≈0.1°for those properties to be expected,consistent with the existing experimental reports.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12304058, 12204073, and 12147102)Guangxi Science and Technology Base and Talent Project (Grant No. 2022AC21077)+1 种基金Natural Science Foundation of Guangxi Province (Grant No. 2024GXNSFBA010229)Foundation of Guangxi University of Science and Technology (Grant No. 21Z52)。
文摘Topological zero-line modes(ZLMs) with spin and valley degrees of freedom give rise to spin, valley and spinvalley transport, which support a platform for exploring quantum transport physics and potential applications in spintronic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current due to the ZLMs in a three-terminal system. We show that with certain combinations of ZLMs, the incident charge current along the interface between different topological phases can be divided into different polarized currents with unit transmittance in two outgoing terminals. As a result, fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. The mechanism of these splitters is attributed to the cooperative effects of the distribution of the ZLMs and the intervalley and intravalley scatterings that are modulated by the wave-vector mismatch and group velocity mismatch. Interestingly, half-quantized transmittance of these scatterings is found in a fully spin-valley-polarized electron beam splitter.Furthermore, the results indicate that these splitters can be applicable to graphene, silicene, germanene and stanene due to their robustness against the spin–orbit coupling. Our findings offer a new way to understand the transport mechanism and investigate the promising applications of ZLMs.
基金the National Key Research and Development Program (Grant No. 2017YFB0405703)the China Government Youth 1000-Plan Talent Program, and the National Natural Science Foundation of China (Grant No. 11474265).
文摘We systematically studied the influence of magnetic field on zero-line modes (ZLMs) in graphene and demonstrated the physical origin of their enhanced robustness by employing noneqnilibrium Green's functions and the Landauer Biittiker formula. We found that a perpendicular magnetic field can separate the wavefunctions of the counter-propagating kink states into opposite directions. Specifically, the separation vanishes at the charge neutrality point and increases as the Fermi level deviates from the charge neutrality point and can reach a magnitude comparable to the wavefunction spread at a moderate field strength. Such spatial separation of oppositely propagating ZLMs effectively suppresses backseattering and is more significant under zigzag boundary condition thail under armchair boundary condition. Moreover, the presence of magnetic field enlarges the bulk gap and suppresses the bound states, thereby further reducing the scattering. These mechanisms effectively increase the mean free paths of the ZLMs to approximately 1 |ini in the presence of a disorder.
基金supported by the National Natural Science Foundation of China(Grant Nos.51672171,51861145315,11804216,and 11974327)The supercomputing services from AM-HPC,the Chinese Scholarship Council,Fundamental Research Funds for the Central Universities(Nos.WK3510000010 and WK2030020032),Anhui Initiative in Quantum Information Technologies.
文摘We study theoretically the construction of topological conducting domain walls with a finite width between AB/BA stacking regions via finite element method in bilayer graphene systems with tunable commensurate twisting angles.We find that the smaller is the twisting angle,the more significant the lattice reconstruction would be,so that sharper domain boundaries declare their existence.We subsequently study the quantum transport properties of topological zero-line modes which can exist because of the said domain boundaries via Green’s function method and Landauer–Büttiker formalism,and find that in scattering regions with triintersectional conducting channels,topological zero-line modes both exhibit robust behavior exemplified as the saturated total transmission Gtot≈2e_(2)/h and obey a specific pseudospin-conserving current partition law among the branch transport channels.The former property is unaffected by Aharonov–Bohm effect due to a weak perpendicular magnetic field,but the latter is not.Results from our genuine bilayer hexagonal system suggest a twisting angle aroundθ≈0.1°for those properties to be expected,consistent with the existing experimental reports.
