Spin-pumping into surface states of topological insulator {\alpha}-Sn, spin to charge conversion at room temperature

TL;DR

This study demonstrates room-temperature spin to charge conversion in topological insulator {\

Contribution

It provides experimental evidence of efficient spin to charge conversion via the Inverse Edelstein Effect in {\

Findings

Longer Inverse Edelstein Effect length than Rashba interfaces

Confirmation of Dirac cone persistence after Ag coverage

Potential for spintronic device applications

Abstract

We present experimental results on the conversion of a spin current into a charge current by spin pumping into the Dirac cone with helical spin polarization of the elemental topological insulator (TI) {\alpha}-Sn[1-3]. By angle-resolved photoelectron spectroscopy (ARPES) we first confirm that the Dirac cone at the surface of {\alpha}-Sn (0 0 1) layers subsists after covering with Ag. Then we show that resonant spin pumping at room temperature from Fe through Ag into {\alpha}-Sn layers induces a lateral charge current that can be ascribed to the Inverse Edelstein Effect[4-5]. Our observation of an Inverse Edelstein Effect length[5-6] much longer than for Rashba interfaces[5-10] demonstrates the potential of the TI for conversion between spin and charge in spintronic devices. By comparing our results with data on the relaxation time of TI free surface states from time-resolved ARPES, we can anticipate the ultimate potential of TI for spin to charge conversion and the conditions to reach it.