In-field logarithmic relaxation of microwave absorption in superconducting Tl sub 2 Ba sub 2 Ca sub 2 Cu sub 3 O sub 1 sub 0 and flux pinning properties

Magnetoabsorption increased rapidly with increasing magnetic field, but decayed as a logarithm of time. Field dependence of the flux pinning potential, estimated from the decay rate, supports the thermal activation model for vortices with intrinsic pinning layers in a quasi-2-D superconductor.