Quantum contributions to the magnetoconductivity of critically disordered superconducting TiN films

Abstract

The onset of superconductivity in the presence of disorder is a fundamental problem of condensed matter physics. Here we investigate the magnetoconductance of disordered (8 > kFl > 1.8) superconducting TiN films above the critical temperature Tc. We show that the magnetoconductivity of moderately disordered films with kFl > 5 is in full agreement with the perturbative theory of quantum contributions to conductivity. We demonstrate that the magnetoconductivity of films with kFl ≲ 5 is also in agreement with the perturbative theory down to temperatures T ≈ 2Tc . The quantitative discrepancy between experiment and theory develops only below temperatures T - 2Tc for films with kFl ≈ 5. This discrepancy can be eliminated if we assume steeper temperature dependence of the Larkin's electron'electron attraction strength, Β(T/Tc). The obtained temperature dependence of electron phase breaking time τ (T/Tc) is in agreement with theoretical predictions for all samples.