MAGNETIC PHASE-TRANSFORMATIONS IN NONSTOICHIOMETRIC IRON PHOSPHIDE

The conditions of appearance and stability of magnetic phases in nonstoichiometric iron phosphide under a pressure of 12 kbar are studied experimentally. The results of the measurements of initial susceptibility and magnetization processes as a function of temperature in fields up to 100 kOe are used as a basis for construction of the generalized P-T-epsilon phase diagram. As the temperature decreases the FM ordering is preceded by the transition from the paramagnetic state to the metamagnetic phase of either MM2 or MM1 type depending on the magnitude of the pressure or the parameter epsilon. The irreversible induction of the FM structure by the magnetic field is revealed in the metastability region of the MM2-FM phase transition. This phenomenon also persists in the case when the MM2 state is the ground state. The phase diagram is restored for the case where the FM phase is hidden in the negative pressure region.