Anisotropy in MgB2 thin film studied by magnetic field dependent complex microwave conductivity

Field and temperature dependent microwave measurements on high quality MgB2 thin film have been performed. From the complex microwave conductivity one can identify the mean-field (MF) coherence length deeply in the mixed state, and the Ginzburg-Landau (GL) coherence length at the transition to the normal state. The analysis reveals the temperature independent anisotropy ratio &D*xMFab/&D*xMFc{approximately equal to}2, and &D*xGLab/&D*xGLc{approximately equal to}2.8. The analysis of depinning frequencies shows collective pinning behavior.