Ferromagnetic State and Phase Transitions

Abstract

Ev idence is summarized attesting that the standard exchange field theory of ferro magnetism by Heisenberg has not been successful. It is replaced by the crystal field and a natural assumption that spin orientation is inexo rably associated with the orientation of its carrier. It follows at once that ferro magnetic state is a property of the crystal structure and that both ferro magnetic phase transitions and magnetization must involve a structural rearrangement. The mechanism of structural rearrangements in solids is nucleation and interface propagation. The new approach accounts consistently for ferro magnetic state and its manifestations.