Temperature dependence of vortex flux pinning in polycrystalline GdBa₂Cu₃O₇

Magnetization measurements were made on a polycrystalline sample of GdBa₂Cu₃O₇ at different temperatures from 4.2 K up to T_C=91 K. The saturated remanent magnetization (M_RS) as a detailed function of temperature (T) was used to study the variation of the vortex flux pinning forces with (T). The sample has been fully saturated by applying a high magnetic field to establish the critical state. Our data reveals that the average vortex flux pinning forces scale according to the following empirical relation of M_RS=at⁷+bt^1/2, where t=1-T/T_C, a, and b are constants.