| 1. |
- Fleckenstein, Christoph, et al.
(författare)
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Formation and detection of Majorana modes in quantum spin Hall trenches
- 2021
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 103:12
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel realization for a topologically superconducting phase hosting Majorana zero modes on the basis of quantum spin Hall systems. Remarkably, our proposal is completely free of ferromagnets. Instead, we confine helical edge states around a narrow defect line of finite length in a two-dimensional topological insulator. We demonstrate the formation of a new topological regime, hosting protected Majorana modes in the presence of s-wave superconductivity and Zeeman coupling. Interestingly, when the system is weakly tunnel coupled to helical edge state reservoirs, a particular transport signature is associated with the presence of a non-Abelian Majorana zero mode.
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| 2. |
- Geissler, F., et al.
(författare)
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Group theoretical and topological analysis of the quantum spin Hall effect in silicene
- 2013
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Silicene consists of a monolayer of silicon atoms in a buckled honeycomb structure. It was recently discovered that the symmetry of such a system allows for interesting Rashba spin-orbit effects. A perpendicular electric field is able to couple to the sublattice pseudospin, making it possible to electrically tune and close the band gap. Therefore, external electric fields may generate a topological phase transition from a topological insulator to a normal insulator (or semimetal) and vice versa. The contribution of the present paper to the study of silicene is twofold. Firstly, we perform a group theoretical analysis to systematically construct the Hamiltonian in the vicinity of the K points of the Brillouin zone and find an additional, electric field induced spin-orbit term, that is allowed by symmetry. Subsequently, we identify a tight-binding model that corresponds to the group theoretically derived Hamiltonian near the K points. Secondly, we start from this tight-binding model to analyze the topological phase diagram of silicene by an explicit calculation of the Z(2) topological invariant of the band structure. To this end, we calculate the Z(2) topological invariant of the honeycomb lattice in a manifestly gauge invariant way which allows us to include S-z symmetry breaking terms-like Rashba spin-orbit interaction-into the topological analysis. Interestingly, we find that the interplay of a Rashba and an intrinsic spin-orbit term can generate a non-trivial quantum spin Hall phase in silicene. This is in sharp contrast to the more extensively studied honeycomb system graphene where Rashba spin-orbit interaction is known to compete with the quantum spin Hall effect in a detrimental way.
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