On the theory of Hc2 anisotropy in cubic superconductors

The anisotropy of the upper critical magnet field Hc2 of cubic type‐II superconductors with anisotropic Fermi surface and anisotropic attractive interaction is investigated. For a separable model interaction explicit results are given on the temperature and impurity dependence of the Hc2 anisotropy of impure metals in the „quasilocal”︁ regime and of clean metals for arbitrary temperatures below Tc. The clean‐limit results agree well with experimental data on Hc2 anisotropy of high‐purity Nb.