Phase diagrams and edge-state transitions in graphene with spin-orbit coupling and magnetic and pseudomagnetic fields

Zhuang, Yu-Chen; Sun, Qing-Feng

doi:10.1103/physrevb.106.165417

Cited by 11 publications

(3 citation statements)

References 75 publications

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“…Due to the regulated linear Dirac dispersion, [1][2][3] graphene-like materials with a honeycomb lattice structure, such as graphene itself, [4] silicene, [5,6] germanene [7,8] and stanene, [9,10] are ideal platforms for investigating fundamental quantum transport physics and have a wide range of applications in device design. It has been found that graphene-like materials can exhibit abundant topological phases under different external fields applied to the whole system, [11][12][13][14][15] and the side potential applied to the boundary of the system is also crucial for generating and manipulating topological phases and corresponding edge states. [16,17] In particular, a large number of zero-line modes (ZLMs) [18][19][20] that can arise from the interface separating different topological phases have been found in addition to outer edge states [11,[21][22][23] induced at the interface between topological phases and the topologically trivial vacuum.…”

Section: Introductionmentioning

confidence: 99%

Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

Lü 吕,

Yang 杨,

Xie 谢

2024

Chinese Phys. B

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Topological zero-line modes (ZLMs) with spin and valley degrees of freedom gives rise to the spin, valley and spin-valley transports, which support a platform to explore the quantum transport physics and potential applications in the spintonic/valleytronic devices. In this work, we investigate the beam-splitting behaviors of the charge current devoted by the ZLMs in a three-terminal system. It shows that with special combinations of the 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, the fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters are generated. And 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, a 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 the robustness against the spin-orbit coupling. Our findings offer a new view to understand the transport mechanism and investigate the promising applications of the ZLMs.

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Section: Introductionmentioning

confidence: 99%

Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

Lü 吕,

Yang 杨,

Xie 谢

2024

Chinese Phys. B

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“…[1][2][3] Analogous to spintronics, valleytronics aim to generate, control, and detect the valley degree of freedom, which have potential applications in semiconductor technologies and quantum information. Many topics of valleytronics have been reported in recent years, including valley-polarized transport, [4] quantum valley Hall effect, [5][6][7] spin-valley locked physics, [8,9] chiral optical selection rules, [10] etc. Because of the Berry phase difference for the two valleys induced by magnetic field, the giant valley splitting and unusual valley crossing are observed in the graphene resonators.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced valley-dependent equal-spin Andreev reflection in Ising superconductor junction

Mao

Sun

2023

Chinese Phys. B

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The Ising spin-orbit coupling could give rise to the spin-triplet Cooper pairs and equal-spin Andreev reflection (AR) in Ising superconductors. Here we theoretically study the valley-dependent equal-spin AR in a ferromagnet/Ising superconductor junction with a circularly polarized light applied to the ferromagnet. Because of the spin-triplet Cooper pairs and the optical irradiation, eight kinds of AR processes appear in the junction, including equal-spin AR and normal AR, the strengthes and properties of which strongly depend on the valley degree of freedom. The AR probabilities for incident electron from the two valleys exhibit certain symmetry with respect to magnetization angle and the effective energy of light. The equal-spin AR and normal AR present different features and resonant behaviors near the superconducting gap edges. Due to equal-spin-triplet Cooper pairs, not only charge supercurrent but also spin supercurrent can transport in the Ising superconductors. The differential spin conductance for electron injecting from the two valleys can be controlled by the circularly polarized light.

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“…With the discovery of a large number of QSHIs, research on the helical edge states has attracted increasing attention, such as the penetration depth of edge states [21], p-n junction [22], finite size effect [23], robustness against the magnetic field [24], and so on. Although theoretical studies have shown that QSHE is robust because of topologically protected helical edge states, it is fundamentally different from the integer quantum Hall effect (IQHE) in terms of the robustness of topological protection.…”

Section: Introductionmentioning

confidence: 99%

Thermal dissipation of the quantum spin Hall edge states in HgTe/CdTe quantum well

Fang,

Zhuang,

Guo

et al. 2023

J. Phys.: Condens. Matter

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Quantum spin Hall eﬀect is characterized by topologically protected helical edge states. Here we study the thermal dissipation of helical edge states by considering two types of dissipation sources. The results show that the helical edge states are dissipationless for normal dissipation sources with or without Rashba spin-orbit coupling in the system, but they are dissipative for spin dissipation sources. Further studies on the energy distribution show that electrons with spin-up and spin-down are both in their own equilibrium without dissipation sources. Spin dissipation sources can couple the two subsystems together to induce voltage drop and non-equilibrium distribution, leading to thermal dissipation, while normal dissipation sources cannot. With the increase of thermal dissipation, the subsystems of electrons with spin-up and spin-down evolve from non-equilibrium ﬁnally to mutual equilibrium. In addition, the eﬀects of disorder on thermal dissipation are also discussed. Our work provides clues to reduce thermal dissipation in the quantum spin Hall systems.

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Phase diagrams and edge-state transitions in graphene with spin-orbit coupling and magnetic and pseudomagnetic fields

Cited by 11 publications

References 75 publications

Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

Fully spin-polarized, valley-polarized and spin-valley-polarized electron beam splitters utilizing zero-line modes in a three-terminal device

Photoinduced valley-dependent equal-spin Andreev reflection in Ising superconductor junction

Thermal dissipation of the quantum spin Hall edge states in HgTe/CdTe quantum well

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