Two-dimensional phase transitions in superconducting thin films

Measurements are reported on the influence of a magnetic field on two-dimensional phase transitions in indium/indium oxide composite superconducting films and on a thermoelectrically generated magnetization in the same system. In an external magnetic field, below the Kosterlitz-Thouless vortex unbinding temperature T/sub c/, the resistive transition is governed by the temperature dependence of vortex mobility of field-generated vortices. The effect of vortex pinning turns out more significant in smaller magnetic fields. In the temperature range between T/sub c/ and the Ginzburg-Landau superconducting transition temperature T/sub c/, data are in good agreement with the universal magnetic field scaling proposed by Minnhagen