Paper detail

A Direct Determination of the Temperature of Overheated Electrons in an Insulator

Highly disordered superconductors, in the magnetic-field-driven insulating state, can show discontinuous current-voltage characteristics. Electron overheating has been shown to give a consistent description of this behavior, but there are other, more exotic, explanations including a novel, superinsulating state and a many-body localized state. We present AC-DC crossed-measurements, in which the application of a DC voltage is applied along our sample, while a small AC voltage is applied in the transverse direction. We varied the DC voltage and observed a simultaneous discontinuity in both AC and DC currents. We show that the inferred electron-temperature in the transverse measurement matches that in the longitudinal one, strongly supporting electron overheating as the source of observed current-voltage characteristics. Our measurement technique may be applicable as a method of probing electron overheating in many other physical systems, which show discontinuous or non-linear current-voltage characteristics.