Switching spin and charge between edge states in topological insulator constrictions
| Autor: | Klaus Richter, Viktor Krueckl |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Physics
Condensed Matter - Mesoscale and Nanoscale Physics Spin polarization Condensed matter physics ddc:530 General Physics and Astronomy Mercury telluride FOS: Physical sciences Charge (physics) Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 530 Physik 73.23.-b 85.35.Ds 85.75.Hh chemistry.chemical_compound chemistry Topological insulator Spin transistor Mesoscale and Nanoscale Physics (cond-mat.mes-hall) Spinplasmonics Spin Hall effect Condensed Matter::Strongly Correlated Electrons Spin-½ |
| DOI: | 10.48550/arxiv.1104.4284 |
| Popis: | Since the prediction of a new topological state of matter in graphene, materials acting as topological insulators have attracted wide attention. Shortly after the theoretical proposal for a mercury telluride (HgTe)-based two-dimensional topological insulator, the observation of the quantum spin Hall effect and non-local edge transport brought compelling experimental evidence for quantized conductance due to edges states. The spin orientation and propagation direction of such helical edge states are inherently connected, providing protection against backscattering. However, these features conversely render controlled spin operations such as spin switching difficult. Here we therefore propose constrictions as connectors between opposite edge (and spin) states in HgTe. We demonstrate how the coupling between edge states, which overlap in the constriction, can be employed both for steering the charge flow into different edge modes and for controlled spin switching. This gives rise to a three-state charge and spin transistor function. Unlike in a conventional spin transistor, the switching does not rely on a tunable Rashba spin-orbit interaction, but on the energy dependence of the edge state wavefunctions. Based on this mechanism, and supported by numerical transport calculations, we present two different ways to control spin- and charge-currents depending on the gating of the constriction. |
| Databáze: | OpenAIRE |
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