Electrical transport signatures of metallic surface state formation in the strongly-correlated insulator FeSb2

TL;DR

This study uncovers the emergence of a metallic surface state in FeSb$_2$ at low temperatures through detailed electrical transport measurements, highlighting a transition from bulk to surface conduction similar to topological Kondo insulators.

Contribution

The paper demonstrates the formation of a metallic surface state in FeSb$_2$ below 5 K using innovative transport measurement configurations, providing new insights into correlated insulators.

Findings

Metallic surface state appears below 5 K in FeSb$_2$

Transition from bulk to surface conduction observed

Similarities with topological Kondo insulators discussed

Abstract

We present local and nonlocal electrical transport measurements of the correlated insulator FeSb$_2$. By employing wiring configurations that delineate between bulk- and surface-dominated conduction, we reveal the formation of a metallic surface state in FeSb$_2$ for temperatures $\lessapprox 5$~K. This result is corroborated by an angular rotation study of this material's magnetotransport, which also shows signatures of the transition from bulk- to surface-dominated conduction over the same temperature interval as the local/nonlocal transport divergence. Notable similarities with the topological Kondo insulator candidate SmB$_6$ are discussed.