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arXiv · 1707.03624

Tunable spin-polarized edge transport in inverted quantum-well junctions

Dimy Nanclares·Leandro R. F. Lima·Caio H. Lewenkopf·Luis G. G. V. Dias da Silva
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Abstract

Inverted HgTe/CdTe quantum wells have been used as a platform for the realization of 2D topological insulators, bulk insulator materials with spin-helical metallic edges states protected by time-reversal symmetry. This work investigates the spectrum and the charge transport in HgTe/CdTe quantum well junctions both in the topological regime and in the absence of time-reversal symmetry. We model the system using the BHZ effective Hamiltonian and compute the transport properties using recursive Green's functions with a finite differences' method. Specifically, we have studied the material's spatially-resolved conductance in a set-up with a gated central region, forming monopolar (n-n$^{\prime}$-n) and heteropolar (n-p-n, n-TI-n) double junctions, which have been recently realized in experiments. We find regimes in which the edge states carry spin-polarized currents in the central region even in the presence of a small magnetic field, which breaks TRS. More interestingly, the conductance displays spin-dependent, Fabry-Perót-like oscillations as a function of the central gate voltage producing tunable, fully spin-polarized currents through the device.

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Dimy Nanclares, Leandro R. F. Lima, Caio H. Lewenkopf, Luis G. G. V. Dias da Silva. 2017-07-12. Tunable spin-polarized edge transport in inverted quantum-well junctions. https://doi.org/10.1103/physrevb.96.155302

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