High-Temperature Large Diamagnetism In Ball-Milled Sr0.6ca0.4cuo2

The observation of a large effective diamagnetic susceptibility of -3.4 X 10(-6) emu g(-1) Oe(-1) up to temperatures above 1000 K in highly deformed ball-milled Sr0.6Ca0.4CuO2 is reported. These samples do not exhibit superconductivity at low temperature. This anomalously strong diamagnetism increases with milling time and reaches a maximum value after 500 h of milling. A model is proposed in which excess holes, introduced during milling, have wave functions that are extended over the CuO2 planes of the crystallites, resulting in large values of the diamagnetic susceptibility.