1212.1204 (Shashank Misra et al.)

Evidence for a universal minimum superfluid response in field-tuned
disordered superconducting films measured using low frequency ac conductivity    [PDF]

Shashank Misra, Lukas Urban, Minsoo Kim, Ganapathy Sambandamurthy, Ali Yazdani

Our measurements of the low frequency ac conductivity in strongly disordered two-dimensional films near the magnetic field-tuned superconductor-to-insulator transition show a sudden drop in the phase stiffness of superconducting order with either increased temperature or magnetic field. Surprisingly, for two different material systems, the abrupt drop in the superfluid density in a magnetic field has the same universal value as that expected for a Berezinskii-Kosterlitz-Thouless transition in zero magnetic field. The characteristic temperature at which phase stiffness is suddenly lost can be tuned to zero at a critical magnetic field, following a power-law behavior with a critical exponent consistent with that obtained in previous dc transport studies on the dissipative side of the transition.

View original: http://arxiv.org/abs/1212.1204