Magnetic relaxation in a superconducting disk

We propose a way of calculating the magnetic relaxation rate Q for anisotropic disk-shaped superconductors in the transverse magnetic field H, taking into account a flux-line curvature. It can be useful in analyzing experimental data on Q for single crystals of high-Tc superconductors. With this method, the explicit formula for Q(H) is derived in the case of an isotropic disk with a creep activation barrier independent of magnetic induction. It is also shown that flux-line curvature in an anisotropic superconducting disk may result in a nonmonotonic Q(H). In addition, as an auxiliary result that may be of interest in itself, the critical state equations for an anisotropic disk are transformed to an easy-to-use form. copyright 1996 The American Physical Society