A valley valve and electron beam splitter

Li, Jing; Zhang, Rui Xing; Yin, Zhenxi; Zhang, Jianxiao; Watanabe, Kenji; Liu, Chaoxing; Zhu, Jun

doi:10.1126/science.aao5989

Cited by 136 publications

(114 citation statements)

References 36 publications

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“…1(a) and 1(b). The fabrication of the devices uses van der Waals transfer stacking, side contacts, and a multi-layer graphite local bottom gate to screen charged impurities [23,31]. The dual-gated region is connected to the side contacts through regions heavily doped by the Si backgate.…”

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confidence: 99%

Metallic Phase and Temperature Dependence of the ν=0 Quantum Hall State in Bilayer Graphene

Yin

et al. 2019

Phys. Rev. Lett.

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The ν = 0 quantum Hall state of bilayer graphene is a fertile playground to realize many-body ground states with various broken symmetries. Here we report the experimental observations of a previously unreported metallic phase. The metallic phase resides in the phase space between the previously identified layer polarized state at large transverse electric field and the canted antiferromagnetic state at small transverse electric field. We also report temperature dependence studies of the quantum spin Hall state of ν = 0. Complex non-monotonic behavior reveals concomitant bulk and edge conductions and excitations. These results provide timely experimental update to understand the rich physics of the ν = 0 state.Bilayer graphene (BLG) in a magnetic field B offers an exciting opportunity to examine the emergence of many-body ground states arising from its multiple internal electronic degrees of freedom. The non-interacting and unbiased ν = 0 possesses eight approximately degenerate Landau levels (LLs) labeled by their spin (↓ and ↑), valley (K and K′) and orbital (N = 0, 1) quantum numbers. The interplay between Coulomb interactions in a perpendicular magnetic field B and layer/ valley polarization driven by an external electric field D gives rise to many-body ground states with various broken symmetries [1-23]. Effective short-ranged interactions, for example, is shown to stabilize a canted spin anti-ferromagnetic (CAF), layer coherent ground state at small D, which transitions to a fully layer (FLP), spin unpolarized state at large D [9,10]. Experiments to date support this scenario, where a conductance peak is commonly associated with the putative CAF/ FLP phase boundary [18,20,[23][24][25]. This line boundary further splits into two branches at high perpendicular magnetic field B > 12 T, with the phase region in between thought to be partially polarized in all indices [20,23,26,27].Even at a moderate B, calculations including more hopping terms and other symmetryallowed electron-electron interaction terms have uncovered a more nuanced picture [11,17,26]. For example, theory shows that a broken-U (1) × U (1) phase that is canted in both spin and valley could be stabilized in certain parameter regimes in the vicinity of the CAF/ FLP phase boundary [26]. Their experimental plausibility remains to be tested.

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confidence: 99%

Metallic Phase and Temperature Dependence of the ν=0 Quantum Hall State in Bilayer Graphene

Yin

et al. 2019

Phys. Rev. Lett.

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“…As shown in Figure 4(a), the MZMs remain stable against various curved domain wall structure, which means one can easily construct various 2D network structures based on the component unit of kink state [46]. Indeed, recently a square lattice structure have been experimentally constructed through engineer kink states [47]. Thus, engineering kink states may provide advantages for constructing network structures to progressively realizing, manipulating, and non-abelian braiding of MZMs.…”

Section: Discussionmentioning

confidence: 99%

Majorana zero modes from topological kink states in the two-dimensional electron gas

Cheng

Liu

et al. 2020

Phys. Rev. B

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Majorana zero modes (MZMs)-bearing potential applications for topological quantum computingare verified in quasi-one-dimensional (1D) Fermion systems, including semiconductor nanowires, magnetic atomic chains, planar Josephson junctions. However, the existence of multi-bands in these systems makes the MZMs fragile to the influence of disorder. Moreover, in practical perspective, the proximity induced superconductivity may be difficult and restricted for 1D systems. Here, we propose a flexible route to realize MZMs through 1D topological kink states by engineering a 2D electron gas with antidot lattices, in which both the aforementioned issues can be avoided owing to the robustness of kink states and the intrinsically attainable superconductivity in high-dimensional systems. The MZMs are verified to be quite robust against disorders and the bending of kink states, and can be conveniently tuned by varying the Rashba spin-orbit coupling strength. Our proposal provides an experimental feasible platform for MZMs with systematic manipulability and assembleability based on the present techniques in 2D electron gas system.

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“…Through the manipulation of domain walls, we show graphene not only a versatile platform supporting multiple topological corner modes in a controlled manner, but also possessing promising applications such as fabricating topological quantum dots composed of gapped topological kink states and topological corner states. Introduction.-The gapless topological kink states have been widely investigated in domain walls (DWs) of graphene-type electronic and classical wave systems [1][2][3][4][5][6][7][8][9]. Generally, there are two different mechanisms of the formation of DWs.…”

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Gapped topological kink states and topological corner states in honeycomb lattice

Yang

Jia

et al. 2020

Science Bulletin

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Based on the tight-binding model calculations and photonic experimental visualization on graphene, we report the domain-wall-induced gapped topological kink states and topological corner states. In graphene, domain walls with gapless topological kink states could be induced either by sublattice symmetry breaking or by lattice deformation. We find that the coexistence of these two mechanisms will induce domain walls with gapped topological kink states. Significantly, the intersection of these two types of domain wall gives rise to topological corner state localized at the crossing point. Through the manipulation of domain walls, we show graphene not only a versatile platform supporting multiple topological corner modes in a controlled manner, but also possessing promising applications such as fabricating topological quantum dots composed of gapped topological kink states and topological corner states.

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A valley valve and electron beam splitter

Cited by 136 publications

References 36 publications

Metallic Phase and Temperature Dependence of the ν=0 Quantum Hall State in Bilayer Graphene

Metallic Phase and Temperature Dependence of the ν=0 Quantum Hall State in Bilayer Graphene

Majorana zero modes from topological kink states in the two-dimensional electron gas

Gapped topological kink states and topological corner states in honeycomb lattice

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