Evidence for a Finite Temperature Insulator

TL;DR

This paper presents experimental evidence of a finite-temperature insulator in amorphous indium-oxide, showing a sharp conductivity drop at low temperatures, supporting theories of finite-T insulating states.

Contribution

The study provides experimental data indicating a finite-temperature insulator phase, highlighting a sharp conductivity transition in amorphous indium-oxide under high magnetic fields.

Findings

Conductivity drops abruptly at T<0.04 K

Approaches zero conductance at low temperatures

Supports theories of finite-T insulator states

Abstract

In superconductors the zero-resistance current-flow is protected from dissipation at finite temperatures (T) by virtue of the short-circuit condition maintained by the electrons that remain in the condensed state. The recently suggested finite-T insulator and the "superinsulating" phase are different because any residual mechanism of conduction will eventually become dominant as the finite-T insulator sets-in. If the residual conduction is small it may be possible to observe the transition to these intriguing states. We show that the conductivity of the high magnetic-field insulator terminating superconductivity in amorphous indium-oxide exhibits an abrupt drop, and seem to approach a zero conductance at T<0.04 K. We discuss our results in the light of theories that lead to a finite-T insulator.