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Absolute magnetic penetration depth of thin-film niobium measured by fluxoid quantization

1993; American Institute of Physics; Volume: 62; Issue: 17 Linguagem: Inglês

10.1063/1.109446

1520-8842

Charles E. Cunningham, G. S. Park, Blas Cabrera, M. E. Huber,

Magnetic properties of thin films

The absolute magnetic penetration depth of a superconducting niobium film is measured using fluxoid quantization. Laser pulses drive part of a thin, planar niobium loop normal, changing its quantum fluxoid state. We determine the total inductance of the loop by measuring the coupling of the fluxoid to a superconducting quantum interference device at various loop temperatures. We fit the temperature dependence of the inductance data to the Bardeen–Cooper–Schrieffer (BCS) theory to determine the magnetic and kinetic inductances. The kinetic inductance is directly related to the penetration depth through the geometry of the loop, and the measured penetration depth agrees well with the BCS theory.