# Anomalously large spin-current voltages on the surface of SmB$_6$

## TL;DR

This study investigates the surface states of SmB$_6$ using a Corbino geometry-based method, revealing unexpectedly large spin-current voltages that challenge current understanding and highlight the need for careful experimental analysis.

## Contribution

It introduces a novel Corbino geometry approach to probe SmB$_6$ surface states and reports unusually large spin-current voltages, emphasizing the importance of ruling out parasitic effects.

## Key findings

- Observed large spin-current voltages exceeding expectations
- Signal behavior consistent with predictions across orientations
- Parasitic effects like stray field-induced voltages are ruled out

## Abstract

The spin-polarized surface states of topological insulators have attracted interest both from a fundamental and applied point of view. A recent proposal describes a method of probing these surface states with ferromagnetic contacts, which was subsequently applied to a variety of materials. In this study, we use this method on the potential topological insulator SmB$_6$ with a new design based on the Corbino geometry. Though the signal behaves as predicted for all orientations of current and magnetic field, its magnitude is much larger than expected. Possible parasitic effects such as stray field-induced Hall voltages are excluded, leaving the origin of the observations uncertain. This corroborates the need for careful analysis when interpreting results of similar experiments.