Effect of weak disorder on the magnetic properties of highly correlated electron systems

The effect of weak disorder on the magnetic properties of highly correlated electron systems is studied by the diagrammatic technique with X operators within the t-J-A model, which combines the t-J with the Anderson model. The generalized random-phase approximation (GRPA) is used to calculate the dynamic magnetic susceptibility, and the condition of its divergence is employed to determine the criteria of paramagnetic phase instability with respect to ferromagnetic and antiferromagnetic ordering. Magnetic phase diagrams are constructed, and the Curie and Néel temperatures are calculated. It is shown that weak disorder in a highly correlated electron system suppresses ferromagnetism and extends antiferromagnetism. Fiz. Tverd. Tela (St. Petersburg) 39, 1609–1615 (September 1997)