Resistance behavior near the magnetic-field-tuned quantum transition in superconducting amorphous In-O films

TL;DR

This study investigates the magnetic-field-induced quantum transition in amorphous In-O films, revealing non-standard resistance behavior and the coexistence of insulating and metallic states near the transition.

Contribution

It provides new insights into the critical resistance behavior and scaling near the quantum transition in amorphous superconducting films, challenging standard models.

Findings

Critical resistance R_c varies linearly with temperature near transition.

The high-field state can be either insulating or metallic.

Critical index y is determined to be 1.2.

Abstract

We have studied the magnetic-field-tuned superconductivity destroying quantum transition in amorphous In-O films with the onset of superconductivity in zero field at about 2 K. At temperatures down to 30 mK the critical resistance R_c=R(T,B_c) has been found to change approximately linearly with temperature, which is in contradiction to a standard description where zero slope dR_c/dT = 0 is assumed near T=0. To make the data R(T,B) collapse in the vicinity of transition against scaling variable (B-B_c)/T^{1/y}, one has either to allow for the intrinsic temperature dependence of R_c or to postulate the critical field B_c to be temperature-dependent B_c(T)-B_c(0)~T^{1+1/y}. We find that the state on the high-field side of the transition can be both insulating and metallic and we determine the critical index y=1.2.