Evidence for surface barriers and their effect on irreversibility and lower-critical-field measurements in Y-Ba-Cu-O crystals

M. Konczykowski; L. I. Burlachkov; Y. Yeshurun; F. Holtzberg

doi:10.1103/PhysRevB.43.13707

Rapid Communication

Evidence for surface barriers and their effect on irreversibility and lower-critical-field measurements in Y-Ba-Cu-O crystals

M. Konczykowski, L. I. Burlachkov, Y. Yeshurun, and F. Holtzberg

Phys. Rev. B 43, 13707(R) – Published 1 June 1991

Abstract

We present measurements of the lowest field for flux penetration of untwinned ${YBa}_{2}$ ${Cu}_{3}$ $O_{7}$ crystals near their transition temperature $T_{c}$ . This field decreases linearly with increasing temperature but exhibits an anomalous change in the slope in close vicinity of $T_{c}$ . Low-dose electron irradiation reduces dramatically the first field for flux penetration. We discuss these results in terms of Bean-Livingston surface barriers which are proposed to be the origin for retardation in flux entry and for irreversible phenomena in the unirradiated crystals.