We discuss measurements of the ac complex conductance of a-MoGe films in the presence of a perpendicular magnetic field. The ac response of vortices in samples with weak pinning reveals an anomaly that is found to be consistent with a dislocation mediated melting in the two-dimensional vortex lattice on short length scales. However, increasing the effects of disorder on the vortex lattice by reducing the sample thickness leads to dominance of thermal-activated creep over melting. With increasing disorder, the length scale associated with the correlations in the vortex lattice is reduced and eventually the melting phenomenon disappears.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics