We report on the direct measurement of the electron-phonon relaxation time, ! eph , in disordered TiN films. Measured values of ! eph are from 5.5 ns to 88 ns in the 4.2 to 1.7 K temperature range and consistent with a T -3 temperature dependence. The electronic density of states at the Fermi level N 0 is estimated from measured material parameters. The presented results confirm that thin TiN films are promising candidate-materials for ultrasensitive superconducting detectors.

We analyze the evolution of the normal and superconducting electronic properties in epitaxial TiN films, characterized by high Ioffe-Regel parameter values, as a function of the film thickness. As the film thickness decreases, we observe an increase of the residual resistivity, which becomes dominated by diffusive surface scattering for d ≤ 20 nm. At the same time, a substantial thicknessdependent reduction of the superconducting critical temperature is observed compared to the bulk TiN value. In such a high quality material films, this effect can be explained by a weak magnetic disorder residing in the surface layer with a characteristic magnetic defect density of ∼ 10 12 cm −2 . Our results suggest that surface magnetic disorder is generally present in oxidized TiN films. arXiv:1903.05009v3 [cond-mat.mtrl-sci]