Flux lattice melting in amorphous composite In/In0 sub x two dimensional superconductors.

The mechanical response of the magnetic flux lattice in two- dimensional In/In0 sub x superconducting films is studied for a variety of normal state sheet resistances. The films are sputtered directly onto a high Q oscillator fabricated from single crystal silicon. The bulk modulus and the mobility of the vortex array contribute to the oscillator response. The melting of the vortex lattice is signaled by a peak in the attenuation and a shift of the resonant frequency of the silicon oscillator, which we associate with the rapid change in mobility of the vortex array near the melting temperature in the weak pinning limit. The zero field extrapolation of the melting temperature can be fit by the Kosterlitz-Thouless model. However, the magnetic field dependence of the melting temperature disagrees with the theoretical picture.