Flux Penetration in an Anisotropic Type-II Superconductor

Calculations are presented for the magnetic induction $B$ and the free energy of an anisotropic type-II superconductor near its upper critical field $H_{c2\mathrm{}}$. It is shown that this field is not necessarily parallel to the externally applied magnetic field H, its direction depending on the direction of H relative to the principal axes of the Ginsburg effective-mass tensor. These results suggest that torque measurements, made on geometrically symmetrical samples, should be useful in determining the upper critical field $H_{c2\mathrm{}}$ as well as the components of the effective-mass tensor.