BCS temperature-dependent superconducting energy gap in domain boundaries of melt-textured YBa[sub 2]Cu[sub 3]O[sub 7]

Attenuation and velocity measurements in low magnetic fields in the superconducting state of a melt-textured sample of YBa[sub 2]Cu[sub 3]O[sub 7] are reported. Changes in both attenuation [alpha] and relative velocity dv/v are observed at the penetration field H[prime][sub c1] of its domain boundaries. The change in dv/v at H[prime][sub c1] appears to be proportional to the repulsive force between vortices. The change in [alpha] at H[prime][sub c1] may be produced by a relaxation process involving superconducting quasiparticles in the vicinity of the normal core of the vortices. Analysis of the relaxation time associated with this process yields a temperature-dependent energy gap which follows the BCS dependence. The relaxation time associated with the process is about 10[sup [minus]11] sec. 19 refs., 10 figs.