Microscopic Derivation of the Kim and Bean State in Pinned Superconductors

We present a microscopic derivation, without electrodynamical assumptions, of B(x,y,H(t)), and Jc(H(t)), in agreement with experiments on strongly pinned superconductors, for a range of values of the density and strength of the pinning sites. We numerically solve the overdamped equations of motion of these flux-gradient driven vortices which can be temporarily trapped at pinning centers. The field is increased (decreased) by the addition (removal) of flux lines at the sample boundary, and complete hysteresis loops can be achieved by using flux lines with opposite orientation.

The top portion of figures (a) and (b) shows a top view of the region where flux lines, indicated by dots, move. The bottom panels show the flux density profile B(x) versus x, averaged over the vertical direction y. (a) Snapshot during the initial ramp-up phase. (b) Snapshot of the remnant magnetization after ramping down the external field.

C. Reichhardt, C. J. Olson, J. Groth, Stuart Field, and Franco Nori
Published in Physical Review B, 52 10441 (1995).

A copy of the paper is avaliable here.

Created by: Jared Groth and Bartholomew Hsu
Last modified: 03/07/97