Vortices and the superconductor-insulator transition

We present results from a study of the temperature ($T$) and magnetic field ($B$) dependence of disordered, superconducting, amorphous indium-oxide thin-films. Application of a perpendicular $B$ weakens superconductivity until, at a well- defined critical $B$, the system is driven into an insulating state. We find that our samples follow a simple power-law dependence on $B$ that holds over a wide range of $T$ and resistance. Surprisingly, this power-law dependence continues, uninterrupted, into the $B$-driven insulating state. These results indicate that vortices play a central role in determining the transport properties of our films.