Correspondence: Reply to "On the understanding of current-induced spin polarization of 3D topological insulators"

TL;DR

This paper discusses the limitations of a model used to interpret spin polarization measurements in topological insulators, emphasizing that it cannot reliably determine the sign of spin polarization due to missing physical contributions.

Contribution

The authors critique an existing model for measuring spin polarization in topological insulators, highlighting its inability to account for all physical effects influencing the measurements.

Findings

The model fails to include separate physical contributions affecting spin polarization sign.

Conflicting experimental results are partly due to model limitations.

Accurate interpretation requires considering multiple physical effects.

Abstract

We reported the first spin potentiometric measurement to electrically detect spin polarization arising from spin-momentum locking in topological insulator (TI) surface states using ferromagnet/tunnel barrier contacts [1]. This method has been adopted to measure the current generated spin in other TI systems [2-10], albeit with conflicting signs of the measured spin voltage [1,2,4,6-10]. Tian et al. wish to use their model as presented in Ref. [4] to determine the sign of the induced spin polarization, and thereby determine whether the claims of various groups to have sampled the topologically protected surface states in bulk TIs are correct. The central point of our Reply is that the model as presented is incapable of doing so because it fails to include separate physical contributions which independently effect the sign of the spin polarization measured.