Measurement of the magnetic penetration depth of a superconducting MgB2 thin film with a large intraband diffusivity

Abstract

We report the temperature dependent magnetic penetration depth lambda (T) and the superconducting critical field Hc2(T) in a 500-nm MgB2 film. Our analysis of the experimental results takes into account the two gap nature of the superconducting state and indicates larger intraband diffusivity in the 3D pi band compared to that in the 2D sigma band. Direct comparison of our results with those reported previously for single crystals indicates that larger intraband scattering in the 3D pi band leads to an increase of lambda. We calculated lambda and the thermodynamic critical field Hc = 2000 Oe employing the gap equations for two-band superconductors. Good agreement between the measured and calculated lamba value indicates the two independent measurements, such as magnetic force microscopy and transport, provide a venue for investigating superconducting properties in multi-band superconductors.