Spin-polarized voltage probes for helical edge state: a model study

Abstract

Theoretical models of a spin-polarized voltage probe (SPVP) tunnel-coupled to the helical edge states (HES) of a quantum spin Hall system (QSHS) are studied. Our first model of the SPVP comprises $N_P$ spin-polarized modes (subprobes), each of which is locally tunnel-coupled to the HES, while the SPVP, as a whole, is subjected to a self-consistency condition ensuring zero average current on the probe. We carry out a numerical analysis which shows that the optimal situation for reading off spin-resolved voltage from the HES depends on the interplay of the probe-edge tunnel-coupling and the number of modes in the probe ($N_P$). We further investigate the stability of our findings by introducing Gaussian fluctuations in {\it{(i)}} the tunnel-coupling between the subprobes and the HES about a chosen average value and {\it{(ii)}} spin-polarization of the subprobes about a chosen direction of the net polarization of SPVP. We also perform a numerical analysis corresponding to the situation where four such SPVPs are implemented in a self-consistent fashion across a ferromagnetic barrier on the HES and demonstrate that this model facilitates the measurements of spin-resolved four-probe voltage drops across the ferromagnetic barrier. As a second model, we employ the edge state of a quantum anomalous Hall state (QAHS) as the SPVP which is tunnel-coupled over an extended region with the HES. A two-dimensional lattice simulation for the quantum transport of the proposed device setup comprising a junction of QSHS and QAHS is considered and a feasibility study of using the edge of the QAHS as an efficient spin-polarized voltage probe is carried out in presence of an optimal strength of the disorder.

arXiv comment13 pages, 14 figures, Revised lattice simulation with new set of parameters

References in corpus (39)

• Spintronics: Fundamentals and applications
• Quantum Spin Hall Effect in Graphene
• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Quantum Spin Hall Effect
• Kwant: a software package for quantum transport
• Spintronics and Pseudospintronics in Graphene and Topological Insulators
• Nonlocal edge state transport in the quantum spin Hall state
• Quantum Spin Hall Effect in Inverted Type II Semiconductors
• The Helical Liquid and the Edge of Quantum Spin Hall Systems
• Quantum Anomalous Hall Effect in Hg${}_{1-y}$Mn${}_y$Te Quantum Wells
• Stability of the quantum spin Hall effect: effects of interactions, disorder, and Z_2 topology
• Spin polarization of the quantum spin Hall edge states
• Imaging currents in HgTe quantum wells in the quantum spin Hall regime
• Kondo effect in the helical edge liquid of the quantum spin Hall state
• Helical edge resistance introduced by charge puddles
• Inelastic electron backscattering in a generic helical edge channel
• Conductance of a helical edge liquid coupled to a magnetic impurity
• Phonon induced backscattering in helical edge states
• Resistance of helical edges formed in a semiconductor heterostructure
• Electrical injection and detection of spin-polarized currents in topological insulator Bi2Te2Se
• Conductivity of a generic helical liquid
• Localization at the Edge of 2D Topological Insulator by Kondo Impurities with Random Anisotropies
• Interplay of exciton condensation and quantum spin Hall effect in InAs/GaSb bilayers
• Proposal for the detection and braiding of Majorana fermions in a quantum spin Hall insulator
• Incoherent transport on the $\nu =2/3$ quantum Hall edge
• Backscattering Between Helical Edge States via Dynamic Nuclear Polarization
• Helical edge states coupled to a spin bath: Current-induced magnetization
• Random Rashba spin-orbit coupling at the quantum spin Hall edge
• Kondo lattice on the edge of a two-dimensional topological insulator
• Stabilization of Quantum Spin Hall Effect by Designed Removal of Time-Reversal Symmetry of Edge States
• Spin polarised scanning tunneling probe for helical Luttinger liquids
• Backscattering in helical edge states from a magnetic impurity and Rashba disorder
• Electrical control of the Kondo effect in a helical edge liquid
• Spin-orbit interactions in a helical Luttinger liquid with a Kondo impurity
• $\pi$ Spin Berry Phase in a Quantum-Spin-Hall-Insulator-Based Interferometer: Evidence for the Helical Spin Texture of the Edge States
• Spin Berry phase in a helical edge state: Sz nonconservation and transport signatures
• Tunable multi-electron Pancharatnam phase in intensity interferometry

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