Superconductor-Insulator Transition by Magnetic-Field-Tuning in Two-Dimensional Films

Abstract

According to the recent scaling theory of the magnetic-fie1d-tuned superconductor-insulator (S-I) transition, the sheet resistance R(T, B) in the two-dimensional superconductors obeys the scaling function with temperature and magnetic field in the vicinity of the S-I transition. To test the scaling behavior experimentally, two types of indium films are studied: one is an amorphous ultrathin film prepared by quench-condensation and the others are granular films composed of two-dimensionally coupled indium particles. Predicted scaling behavior is observed both in the amorphous film and in the granular one with the average grain sizes ($(\bar d)$) of 140 A, while it is not found in the granular one with $(\bar d) = 280$ A.