PRESSURE-DEPENDENCE OF THE VERWEY TEMPERATURE OF FE3-YO4 OBTAINED BY MAGNETIC-PERMEABILITY MEASUREMENTS

The magnetic permeability of stoichiometric or non-stoichiometric magnetite (Fe3-O(y)4) at high pressures has been measured in a piston-cylinder apparatus. The Verwey transition temperature decrease with pressure at rates of 2.7+/-0.1 KGPa-1 for y = 0.000, 2.49+/-0.07 for y = 0.0051, 2.3+/-0.1 for y = 0.0063, 2.55+/-0.03 for y = 0.0070, 2.0+/-0.1 for y = 0.012, 2.0+/-0.2 for y = 0.019, 2.44+/-0.08 for y = 0.024, 2.4+/-0.1 for y = 0.033 and 2.15+/-0.08 for y = 0.034. A phonon-induced correlated electron transfer mechanism by Srivastava can explain the pressure dependence of the Verwey transition temperature. The temperature of the peak of temperature-permeability curve for each y decreases with increasing pressure.