S. Salem-sugui et Kc. Goretta, Study of flux-creep in bulk melt-textured YBa2Cu3Ox in the regime of individual pinning, J SUPERCOND, 12(5), 1999, pp. 661-665
Magnetic relaxation, with magnetic fields applied parallel to the c axis, w
as measured in a high-quality melt-textured YBa2Cu3Ox bar. Zero-field-coole
d magnetization-versus-time data were obtained within a regime of field and
temperatures dominated by single vortex pinning. The activation pinning en
ergy U = U-M was calculated from experimental data and compared to U = U(0)
ln(J(c)/J), where U, is a constant, J(c) is the critical current density, a
nd J the current density. This expression for U obtains within the individu
al pinning regime. A logarithmic dependence of U-M on J was found, and the
data indicated that a scaling function of U-M, g(T/T-c) = (1 - T/T-c)(1/2),
was appropriate for describing the single-vortex pinning regime.