Singular Volume Dependence of Transition-Metal Magnetism

The transition from nonmagnetic to magnetic behavior in transition-metal ferromagnets is studied by analysis of all possible volume evolutions of the variation of the total energy with magnetic moment. In contrast to a large body of previous work, magnetic transitions are shown to be necessarily singular, and usually multivalued and discontinuous. Self-consistent spin-polarized energy-band calculations for bcc nickel, fcc cobalt, bcc vanadium, and fcc iron are presented as examples supporting and illustrating the general conclusions.