550 research outputs found
On temperature-dependent anisotropies of upper critical field and London penetration depth
We show on a few examples of one-band materials with spheroidal Fermi
surfaces and anisotropic order parameters that anisotropies of the
upper critical field and of the London penetration depth
depend on temperature, the feature commonly attributed to multi-band
superconductors. The parameters and may have
opposite temperature dependencies or may change in the same direction depending
on Fermi surface shape and on character of the gap nodes. For two-band systems,
the behavior of anisotropies is affected by the ratios of bands densities of
states, Fermi velocities, anisotropies, and order parameters. We investigate in
detail the conditions determining the directions of temperature dependences of
the two anisotropy factors
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