Magnetization experiments around T sub(c) in cuprate superconductors: Thermal fluctuation, random orientation and inhomogeneity effects

We present some measurements of the crossing point of the excess magnetization vs. temperature curves, ( Delta M*, T*), and of the Meissner fraction, Chi super(FC)(T), in granular La sub(1.9)Sr sub(0.1)CuO sub(4) (LaSCO) samples, before and after grain alignment. These results show that once Delta M* and Chi super(FC) are adequately and separately corrected for random grain orientation and demagnetizing effects, the remaining extrinsic effects on Delta M* sub(ab) (associated with structural and, mainly, stoichiometric inhomogeneities) may be taken into account through Chi super(F) sub(a) super(C) sub(b)(T*). The intrinsic Delta M* sub(ab) values agree with the predictions based on thermal fluctuations of pancakes.