Flux-lattice melting in amorphous composite In/InO/sub x/ two-dimensional superconductors

We report the phase diagram for magnetic fluxoids in two-dimensional In/InO/sub x/ superconducting films. The films are sputtered directly onto high-Q silicon oscillators. The melting of the vortex lattice is signaled by a peak in the attenuation and a shift of the resonant frequency of the oscillator, caused by the rapid change in mobility of the vortex array. The zero-field limit of the melting temperature can be fitted by the Kosterlitz-Thouless model. However, the magnetic field dependences disagree with the current theoretical picture