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

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 range of temperature above transition temperature (T_c), the coexistence of SF-mediated positive MR and WL-led negative MR in different ranges of magnetic fields and a crossover from positive MR to negative MR with an increase in temperature are reported herein. The crossover temperature coincides with a characteristic temperature (T_max) at which a resistance peak appears in the zero-field R(T). The resistance peak and associated magnetoresistance anomalies are addressed using quantum corrections to 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 T_c, SFs dominate; with an increase in temperature, the contributions from both become comparable; and finally, at T_max, 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.