Robust local and non-local transport in the Topological Kondo Insulator SmB$_{6}$ in the presence of high magnetic field

TL;DR

This study investigates the surface transport properties of SmB$_6$, a topological Kondo insulator, revealing robust surface conduction with signatures of helical spin states, unaffected by high magnetic fields, through combined experimental and simulation approaches.

Contribution

It provides a detailed quantitative analysis of surface transport in SmB$_6$, distinguishing contributions from different channels and demonstrating the robustness of surface states under high magnetic fields.

Findings

Large non-local surface signals at low temperatures.

Surface transport insensitive to high magnetic fields.

Signatures of helical spin states and inter-band scattering.

Abstract

SmB$_6$ has been predicted to be a Kondo Topological Insulator with topologically protected conducting surface states. We have studied quantitatively the electrical transport through surface states in high quality single crystals of SmB$_6$. We observe a large non-local surface signal at temperatures lower than the bulk Kondo gap scale. Measurements and finite element simulations allow us to distinguish unambiguously between the contributions from different transport channels. In contrast to general expectations, the electrical transport properties of the surface channels was found to be insensitive to high magnetic fields. Local and non-local magnetoresistance measurements allowed us to identify definite signatures of helical spin states and strong inter-band scattering at the surface.