Abstract
Recent measurements of the anisotropy of the upper critical field on single crystals have shown a puzzling strong temperature dependence. Here, we present a calculation of the upper critical field based on a detailed modeling of band structure calculations that takes into account both the unusual Fermi surface topology and the two gap nature of the superconducting order parameter. Our results show that the strong temperature dependence of the anisotropy can be understood as an interplay of the dominating gap on the band, which possesses a small -axis component of the Fermi velocity, with the induced superconductivity on the -band possessing a large -axis component of the Fermi velocity. We provide analytic formulas for the anisotropy ratio at and and quantitatively predict the distortion of the vortex lattice based on our calculations.
- Received 9 December 2002
DOI:https://doi.org/10.1103/PhysRevLett.91.017001
©2003 American Physical Society