Thickness magnetic field phase diagram at the superconductor-insulator transition in 2D

The superconductor-insulator transition in ultrathin films of amorphous Bi has been tuned by changing both film thickness and magnetic field on the sa me-set of films. A thickness-magnetic field phase diagram has been mapped i n the T = 0 limit. A finite size scaling analysis has been carried out to d etermine the critical exponent product vz, which was found to be 1.2 +/- 0. 2 and 1.4 +/- 0.2 for the thickness-tuned transitions in zero and finite ma gnetic fields, respectively. These are different from the exponent found fo r the magnetic-held-tuned transition in the same system, 0.7 +/- 0.2.