Spin-Polarized Tunneling Study on Spin-Momentum Locking in the Topological Insulators

TL;DR

This study experimentally measures charge-spin conversion in topological insulators by spin-polarized tunneling, comparing materials and energy dependence, revealing large spin polarization crucial for spintronic applications.

Contribution

It introduces an experimental method to determine charge-spin conversion efficiency in TIs and verifies the surface-state origin of spin signals across different materials.

Findings

Verified giant spin signals originate from topological surface states

Demonstrated energy dependence of effective spin polarization in Bi2Se3

Provided insights for optimizing TIs for room-temperature spintronics

Abstract

We demonstrate that the charge-spin conversion efficiency of topological insulators (TI) can be experimentally determined by injecting spin-polarized tunneling electrons into a TI. Through a comparative study between bismuth selenide and bismuth antimony telluride, we verified the topological-surface-state origin of the observed giant spin signals. By injecting energetic electrons into bismuth selenide, we further studied the energy dependence of the effective spin polarization at the TI surface. The experimentally verified large spin polarization, as well as our calculations, provides new insights into optimizing TI materials for near room-temperature spintronic applications.