Gate-controlled Spin Extraction from Topological Insulator Surfaces

• Published in: arXiv.org
• Main Authors: Asgharpour, Ali, Gorini, Cosimo, Essert, Sven, Richter, Klaus, Adagideli, İnanç
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 28.01.2020
• Subjects: Bismuth; Electric fields; Electronic devices; Holes (electron deficiencies); Locking; Momentum; Physics - Mesoscale and Nanoscale Physics; Quantum wires; Spintronics; Topological insulators; Topology
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2001.10359

Spin-momentum locking, a key property of the surface states of three-dimensional topological insulators (3DTIs), provides a new avenue for spintronics applications. One consequence of spin-momentum locking is the induction of surface spin accumulations due to applied electric fields. In this work, we investigate the extraction of such electrically-induced spins from their host TI material into adjoining conventional, hence topologically trivial, materials that are commonly used in electronics devices. We focus on effective Hamiltonians for bismuth-based 3DTI materials in the \({\rm Bi}_2{\rm Se}_3\) family, and numerically explore the geometries for extracting current-induced spins from a TI surface. In particular, we consider a device geometry in which a side pocket is attached to various faces of a 3DTI quantum wire and show that it is possible to create current-induced spin accumulations in these topologically trivial side pockets. We further study how such spin extraction depends on geometry and material parameters, and find that electron-hole degrees of freedom can be utilized to control the polarization of the extracted spins by an applied gate voltage.