engleski

Microwave study of magnetic field penetration parallel to thin niobium films

Complex conductivity of high quality niobium thin films has been investigated by microwave technique in parallel static magnetic field. Mechanism of microwave response substantially changes from ultra-thin to thick film regime. For the thinnest film no vortices can be formed and microwave penetration is defined by strength of superconducting order parameter which varies with applied magnetic field. The thickest film measured allows formation of several rows of vortices. Microwave disipation is dominated by dynamics of vortices which is strongly affected by size effects. Results have been compared with generalised models of complex conductivity for low – dimensional superconductor in mixed state following earlier considerations of other authors. Discussion of dynamical characteristics of vortices is given for measured samples.

microwave response; thin film; mixed state; parallel field

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