ABOUT THE EFFECT OF PRESSURE AND VOLUME EXPANSION ON THE TRANSITION FROM ANTIFERROMAGNETIC TO FERROMAGNETIC STATE IN SOME METAL-ALLOYS

We report a simplified and unifying picture of the different physical contributions to magnetic transitions in itinerant magnetic systems. W hen the antiferro to ferromagnetic transition encompasses a significan t volume expansion, it is shown that the density of states at the Ferm i level is much more sensitive to the unit cell expansion than other t erms, such as spatial polarization, and can actually control the trans ition. The predictions of this model are shown to be in good agreement with experimental trends, particularly with the measured dependence o f the transition temperature with external pressure and external magne tic field.