Scaling structure of magnetization anomalies in high-temperature superconductors

An explanation for the magnetization anomalies recently measured in Y-B-Cu-O and (La, Sr)2CuO4 single crystals is provided. This explanation considers the impact of the disordered state and percolation effects in these materials. The scaling behaviour of the low-field minimum in the magnetization curves (Hmin) as a function of the oxygen deficiency parameter (δ) is deduced. In addition, the temperature-dependence of the secondary peak observed in magnetization curves of (La, Sr)2CuO4 single crystals was found to be consistent with the experimental measurements. The model takes into account the random nature of the defect distribution in the two-dimensional plane and the percolation effects due to grain size distributions.