Use of a Phonon Probe to Determine the Magnetic Dependence of the Superconducting Gap
Superconducting thin films in a magnetic field have been explored in a number of experimental ways including tunnel effect, thermal conductivity, and microwave absorption. Most of these effects, especially at finite temperature, involve the whole of the excitation spectrum, and the minimum, or gap, is usually deduced by assuming a BCS-type density of states dependent upon the magnetic field only through the order parameter (1). In fact the density- of -states functions found experimentally (2) do not agree with this simple model, so that an independent measurement seems useful.
KeywordsMicrowave Helium Coherence Verse
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