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

Author(s)

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

• Document type: Journal article
• Source: PHYSICAL REVIEW B; v. 96, n. 15, p. 9-pg., 2017-10-04.

Abstract

Inverted HgTe/CdTe quantum wells have been used as a platform for the realization of two-dimensional topological insulators, bulk insulator materials with spin-helical metallic edge states protected by time-reversal symmetry. This paper 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 Bernevig-Hughes-Zhang 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 setup with a gated central region, forming monopolar (n-n'-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 time-reversal symmetry. More interestingly, the conductance displays spin-dependent, Fabry-Perot-like oscillations as a function of the central gate voltage producing tunable, fully spin-polarized currents through the device. (AU)

• FAPESP's process: 16/18495-4 - Electronic transport and correlation effects in topological materials
• Grantee: Luis Gregório Godoy de Vasconcellos Dias da Silva
• Support Opportunities: Regular Research Grants