Spin current generator based on topological insulator coupled to ferromagnetic insulators

M J Ma,S G Tan,Z B Siu,M B A Jalil,Y Li

doi:10.1063/1.4751255

Abstract

We propose a spin current generator based on a topological insulator current-in-plane spin valve, consisting of a 3D topological insulator sandwiched between two ferromagnetic insulator layers. The “on” and “off” states of the spin current can be toggled by switching the magnetization configuration of the two ferromagnetic insulator layers which are coupled to the surface states of the topological insulator.

Highlights

Spintronic devices[1,2,3,4] operate based on the manipulation of electron spin orientation and transport by magnetic or electrical fields, so as to provide enhanced functionality over conventional electronic devices
Our proposed TI-based spin current generator is shown schematically in Fig. 1, and consists of a 3D TI layer sandwiched between two ferromagnetic insulator (FI) layers, and contacted to normal metal (NM) source and drain electrodes
The spin conductance σ s monotonically decreases as the magnetization orientation θ of the top FI layer is varied over the range of 0 < θ < π, and this trend underlies the operation of the TI-based spin current generator

Summary

INTRODUCTION

Spintronic devices[1,2,3,4] operate based on the manipulation of electron spin orientation and transport by magnetic or electrical fields, so as to provide enhanced functionality over conventional electronic devices. The spin-up conductance would exceed the corresponding spin-down conductance due to the energy split, as a result of coupling between the FI moments and the conduction electrons in the surface states of the TI. The rest of the paper is organized as follows: In Sec. II, we introduce the Hamiltonian of the system, and evaluate the spin-dependent transport in the system by solving the electron wave functions in the TI, and matching them at the TI-NM interfaces. A brief summary is provided at the end of the paper

THEORY

RESULTS AND DISCUSSION

CONCLUSION