REVERSIBLE AND IRREVERSIBLE FEATURES IN MAGNETIZATION ROTATION EXPERIMENTS

Magnetic anisotropy measurements have been performed in both zero-field-cooled and field-cooled states of two melt texture grown (MTG) superconductors. Hysteresis loops taken at various orientations (theta) of the c axis with respect to field H, indicate a dominant contribution of the c-axis magnetization for theta less-than-or-equal-to 60-degrees. Wider hysteresis loops indicative of higher pinning are obtained for H parallel to c. The magnetization rotation experiments at higher fields (H = 500, 1000 Oe) are observed to reflect the intrinsic anisotropy of magnetization. The magnetization oscillates reversibly as long as the sense of rotation of the sample is not reversed. Reversal of rotation sense leads to irreversibilities, which have been studied as a function of theta and temperature, and their relation to flux line disorder and defects is discussed.