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

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 $⪅5$~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.