Interplay between superconducting fluctuations and weak localization in disordered TiN thin films

TL;DR

This study investigates how superconducting fluctuations and weak localization interact in disordered TiN thin films, revealing their competing effects on magnetoresistance and resistance peaks near the transition temperature.

Contribution

It introduces a method to distinguish and analyze the individual roles of superconducting fluctuations and weak localization in two-dimensional disordered superconductors.

Findings

Superconducting fluctuations dominate just above Tc.

Weak localization effects become prominent at higher temperatures.

A crossover from positive to negative magnetoresistance occurs with increasing temperature.

Abstract

The interplay between superconducting fluctuations (SFs) and weak localization (WL) has been probed by temperature dependent resistance [R(T)] and magnetoresistance (MR) measurements in two-dimensional disordered superconducting TiN thin films. Within a narrow band of temperature above the transition temperature Tc, the coexistence of SFs-mediated positive MR and WL-led negative MR in different range of magnetic field, as well as a crossover from positive to negative MR with increasing temperature are reported here. The crossover temperature coincides with a characteristic temperature (Tmax) at which a resistance peak appears in the zero-field R(T). The resistance peak and the associated magnetoresistance anomalies are addressed by using the quantum corrections to the conductivity (QCC) theory. We show that WL can be accounted for the observed negative MR. By introducing individual coefficients to both SFs and WL contributions, the dominance of one over the other is monitored with respect to temperature. It is observed that just above the Tc, SF dominates and with increasing temperature, the contributions from the both become comparable and finally, at Tmax, WL takes over completely. The presented approach may be adopted to compare various quantum contributions in two-dimensional superconductors particularly in the regime where both SFs and WL are pronounced.