Electric and magnetic properties of the unconventional insulator FeSb₂

This talk shall examine anomalous insulating and metallic signatures of FeSb₂. In our electrical transport measurements, we observe clear signatures of a metallic surface state at low temperatures. This offers a promising setting to explore the effects of strongly correlated 2D physics. Furthermore, despite being a bulk electrical insulator, we detect quantum oscillations in the bulk magnetisation under high applied magnetic fields, similar to previous observations in the analogous materials SmB₆ and YbB₁₂. Importantly, unlike in those materials we also uncover a strong connection between the unconventional insulating quantum oscillations in FeSb₂ and features in the background magnetisation. Our results point strongly to a magnetic origin for the phenomenon of insulating quantum oscillations in unconventional insulators.