Measurements of the Magnetic-Field-Tuned Conductivity of Disordered Two-Dimensional ${\mathrm{Mo}}_{43}{\mathrm{Ge}}_{57}$ and ${\mathrm{InO}}_{x}$ Superconducting Films: Evidence for a Universal Minimum Superfluid Response

Measurements of the Magnetic-Field-Tuned Conductivity of Disordered Two-Dimensional ${Mo}_{43} {Ge}_{57}$ and ${InO}_{x}$ Superconducting Films: Evidence for a Universal Minimum Superfluid Response

S. Misra, L. Urban, M. Kim, G. Sambandamurthy, and A. Yazdani

Phys. Rev. Lett. 110, 037002 – Published 14 January 2013

Abstract

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 a 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.

Received 18 June 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.037002

Authors & Affiliations

S. Misra¹, L. Urban^1,2, M. Kim³, G. Sambandamurthy³, and A. Yazdani^1,*

¹Joseph Henry Laboratories and Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
²Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
³Department of Physics, University at Buffalo, The State University of New York, Buffalo, New York 14260, USA