Crossover of Magnetoresistance from Fourfold to Twofold Symmetry in SmB6 Single Crystal, a topological Kondo insulator

TL;DR

This study observes a temperature-dependent crossover in magnetoresistance symmetry in SmB6, revealing a transition from bulk to surface states and suggesting the emergence of topological nematic states in this Kondo insulator.

Contribution

It reports the first observation of a crossover from fourfold to twofold symmetry in magnetoresistance oscillations in SmB6, indicating a transition from bulk to surface states and potential nematic order.

Findings

Fourfold symmetric MR oscillations observed above 8 K

C4 symmetry weakens and C2 symmetry appears below 8 K

Crossover from bulk to surface states in SmB6

Abstract

Topological Kondo insulators have been attracting great attention from the condensed-matter physics community due to their fascinating topological and strongly correlated properties. Here, we report angle-dependent c-axis magnetoresistance (MR) oscillations in a Kondo insulator, SmB6 single crystal, in a magnetic field of up to 13 T rotated in the ab-plane. Four-fold symmetric MR oscillations are first observed above 8 K, which result from the four-fold (C4) degeneracy of the bulk Fermi surface of SmB6. With decreasing temperature down to 2.3 K, the C4 symmetry of the MR oscillations gradually weakens and C2 symmetry appears. This demonstrates a crossover from three-dimensional bulk states to two-dimensional surface states and implies the possible emergence of topological nematic states. Our experimental observations shed new light on the metallic surface states and nematic states in the Kondo insulator SmB6.