Superconducting phase transitions in disordered NbTiN films

M V Burdastyh; S V Postolova; T Proslier; S S Ustavshikov; A V Antonov; V M Vinokur; A Yu Mironov

doi:10.1038/s41598-020-58192-3

Superconducting phase transitions in disordered NbTiN films

Sci Rep. 2020 Jan 30;10(1):1471. doi: 10.1038/s41598-020-58192-3.

Authors

M V Burdastyh^{1

2}, S V Postolova^{1

3}, T Proslier⁴, S S Ustavshikov³, A V Antonov³, V M Vinokur⁵, A Yu Mironov^{1

2}

Affiliations

¹ A. V. Rzhanov Institute of Semiconductor Physics SB RAS, 13 Lavrentjev Avenue, Novosibirsk, 630090, Russia.
² Novosibirsk State University, Pirogova str. 2, Novosibirsk, 630090, Russia.
³ Institute for Physics of Microstructures RAS, GSP-105, Nizhny Novgorod, 603950, Russia.
⁴ Institut de recherches sur les lois fundamentales de l'univers, Commissariat de l'énergie atomique et aux énergies renouvelables-Saclay, Gif-sur-Yvette, France.
⁵ Materials Science Division, Argonne National Laboratory, 9700 S. Cass Ave, Argonne, IL, 60439, USA. vinokour@anl.gov.

Abstract

Suppression of superconductivity in disordered systems is a fundamental problem of condensed matter physics. Here we investigate superconducting niobium-titanium-nitride (Nb_1-xTi_xN) thin films grown by the atomic layer deposition (ALD) with slightly different growth process parameters. We observe a smooth crossover from the disorder-driven superconductor-normal metal transition (SMT) to the superconductor-insulator transition (SIT) via the intermediate Bose metal state detected by the low-temperature saturation of the temperature dependence of the sheet resistance. We demonstrate that the SIT via the intervening Bose metal state occurs if the sheet resistance of the film in the maximum, R_max prior to the superconducting drop of R(T), exceeds R_q = h/4e².