Nonequilibrium transport near the superconducting transition in TiN films

The linear and nonlinear conductions of titanium nitride films with the thickness $d \leq 10$nm have been studied experimentally in the region of superconducting transitions. It has been shown that the inclusion of all quantum contributions to the conductivity at temperatures above the critical temperature of the superconducting transition $T_c$ makes it possible to completely describe the temperature dependence of the conductivity measured in the linear regime, and the nonlinear behavior of the current-voltage characteristics is in complete agreement with the classical model of the heating of an electron gas in metals. The electron-phonon coupling constant has been determined. The analysis of the linear and nonlinear conductivities at temperatures below $T_c$ shows that the transition to a superconducting state occurs through the Berezinskii–Kosterlitz–Thouless mechanism.