Foltyn SR, and
Dept. of Phys. Purdue Univ., West Lafayette, IN, USA.
Correlation of surface topography and flux pinning in superconducting YBaCuO
Journal of Applied Physics, vol.71, no.10, 15 May 1992, pp.5099-102. USA.
The surface topography of YBa/sub 2/Cu/sub 3/O/sub 7/ thin films prepared by
pulsed laser deposition is studied by atomic force microscopy and scanning
tunneling microscopy. The possible contributions from observed structural
features to the critical current density J/sub c/ are discussed. It is shown
that the contribution of the screw dislocations associated with some
structures can be either repulsive or attractive, depending on the dominant
pinning mechanism. At low magnetic fields (to about 0.26 kOe) these
dislocations can account for the observed critical current density values
(J/sub c/>10/sup 11/ A/m/sup 2/) while for larger fields the higher-density
steplike growth structures can account for significant values of J/sub c/. It
is shown that the pinning strength associated with pinning at steps varies
inversely with thickness. (26 References).