The response to an alternating field of a slab of flux-permeated superconducting material with a local electrodynamic response law E∝‖J${\mathrm{\Vert }}^{\mathrm{\sigma }}$J is obtained numerically. Fundamental and third-harmonic components of the susceptibility are reported as functions of σ and slab thickness. The third-harmonic component is always smaller than in the critical-state model, but not much smaller if σ≫1. If the slab is thick enough, and σ>0 the field is totally extinguished at a finite depth. In that case it gradually adopts a self-replicating, nonsinusoidal wave form whose amplitude diminishes according to a power law while the phase lag diverges logarithmically.

• Received 21 June 1993

DOI:https://doi.org/10.1103/PhysRevB.49.1466