Magnetoresistance evidence on surface state and field-dependent bulk gap in Kondo insulator SmB6

TL;DR

This study investigates the magnetoresistance in SmB6, revealing a surface state and a field-dependent bulk gap, supporting the topological Kondo insulator scenario through high-field measurements up to 55 Tesla.

Contribution

It provides experimental evidence of a surface state and field-dependent bulk gap in SmB6, advancing understanding of its topological properties and low-temperature transport behavior.

Findings

Identification of a two-dimensional surface state via angular-dependent magnetoresistance.

Extraction of a bulk gap with a critical magnetic field of 196 T.

Confirmation of the topological Kondo insulator scenario in SmB6.

Abstract

Recently, the resistance saturation at low temperature in Kondo insulator SmB6, a long-standing puzzle in condensed matter physics, was proposed to originate from topological surface state. Here,we systematically studied the magnetoresistance of SmB6 at low temperature up to 55 Tesla. Both temperature- and angular-dependent magnetoresistances show a similar crossover behavior below 5 K. Furthermore, the angular-dependent magnetoresistance on different crystal face confirms a two-dimensional surface state as the origin of magnetoresistances crossover below 5K. Based on two-channels model consisting of both surface and bulk states, the field-dependence of bulk gap with critical magnetic field (Hc) of 196 T is extracted from our temperature-dependent resistance under different magnetic fields. Our results give a consistent picture to understand the low-temperature transport behavior in SmB6, consistent with topological Kondo insulator scenario.