Universal scaling for the spin-electricity conversion on surface states of topological insulators

TL;DR

This study demonstrates efficient spin-electricity conversion on topological insulator surface states, with enhanced signals at lower temperatures and in samples with higher surface state mobility, advancing spintronic applications.

Contribution

It provides experimental evidence of surface-dominated spin-electricity conversion in topological insulators using a novel trilayer structure with negligible magnetic proximity effects.

Findings

Voltage signals increase at lower temperatures

Higher conversion efficiency in samples with higher surface state mobility

Surface transport dominates the spin-electricity conversion

Abstract

We have investigated spin-electricity conversion on surface states of bulk-insulating topological insulator (TI) materials using a spin pumping technique. The sample structure is Ni-Fe|Cu|TI trilayers, in which magnetic proximity effects on the TI surfaces are negligibly small owing to the inserted Cu layer. Voltage signals produced by the spin-electricity conversion are clearly observed, and enhanced with decreasing temperature in line with the dominated surface transport at lower temperatures. The efficiency of the spin-electricity conversion is greater for TI samples with higher resistivity of bulk states and longer mean free path of surface states, consistent with the surface spin-electricity conversion.