Hall coefficient diagnostics of surface state in pressurized SmB6

TL;DR

This study uses high-pressure Hall coefficient measurements to identify and analyze the surface state in SmB6, revealing a peak in RH(T) as a surface conduction fingerprint and exploring the material's magnetic and metallic phases under pressure.

Contribution

First high-pressure Hall coefficient measurements in SmB6 demonstrating RH(T) peak as a surface state diagnostic and analyzing phase transitions up to 37 GPa.

Findings

RH(T) peak indicates surface conduction

Surface state persists up to 10 GPa

No superconductivity observed in metallic phase

Abstract

In this study, we report the first results of the high-pressure Hall coefficient (RH) measurements in the putative topological Kondo insulator SmB6 up to 37 GPa. Below 10 GPa, our data reveal that RH(T) exhibits a prominent peak upon cooling below 20 K. Remarkably, the temperature at which surface conduction dominates coincides with the temperature of the peak in RH(T). The temperature dependent resistance and Hall coefficient can be well fitted by a two-channel model with contributions from the metallic surface and the thermally activated bulk states. When the bulk of SmB6 becomes metallic and magnetic at ~ 10 GPa, both the RH(T) peak and the resistance plateau disappear simultaneously. Our results indicate that the RH(T) peak is a fingerprint to diagnose the presence of a metallic surface state in SmB6. The high-pressure magnetic state of SmB6 is robust to 180 GPa, and no evidence of superconductivity is observed in the metallic phase.