title: Role of the vortex-core energy on the Berezinskii-Kosterlitz-Thouless transition in thin films of NbN.
abstract: We analyze the occurrence of the Berezinskii-Kosterlitz-Thouless (BKT) transition in thin films of NbN at various film thickness, by probing the effect of vortex fluctuations on the temperature dependence of the superfluid density below T(BKT) and of the resistivity above T(BKT). By direct comparison between the experimental data and the theory, we show the crucial role played by the vortex-core energy in determining the characteristic signatures of the BKT physics, and we estimate its dependence on the disorder level. Our work provides a paradigmatic example of BKT physics in a quasi-two-dimensional superconductor.
authors.affiliation: Tata Institute of Fundamental Research, Colaba, Mumbai, India.
authors.forename: Mintu
authors.initials: M
authors.lastname: Mondal
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Kumar
authors.forename: Madhavi
authors.initials: M
authors.lastname: Chand
authors.forename: Anand
authors.initials: A
authors.lastname: Kamlapure
authors.forename: Garima
authors.initials: G
authors.lastname: Saraswat
authors.forename: G
authors.initials: G
authors.lastname: Seibold
authors.forename: L
authors.initials: L
authors.lastname: Benfatto
authors.forename: Pratap
authors.initials: P
authors.lastname: Raychaudhuri