| Abstract Scope |
The Fe2P intermetallic compound, is a prototypical example of a first order ferromagnetic phase transition, known since the 1980s to exhibit a sharp, but weak, FOMT at 216 K (-57°C)[1]. In this hexagonal system, the Fe atoms occupy two inequivalent atomic positions, referred to as 3f (in a tetrahedral environment of non-metallic atoms) and 3g (in a pyramidal environment). Also for P we find two distinct lattice sites 1a and 2b. One intriguing aspect is the strong reduction (partial quenching) in the magnetic moments of the iron atoms on the 3f sites when TC is crossed from the ferromagnetic to the paramagnetic state, whereas there is only a limited decrease on the 3g site. This observation has led to a cooperative description of the FOMT, linking the loss of long-range magnetic order at TC with the loss of local moments on the 3f site[2]. Replacing Fe and or P by other elements leads to a rich variety of phenomena.
[1]. In O. Beckman et al., Specific Heat of the Ferromagnet Fe2P. Physica Scripta 25 (1982) 679-681;
[2]. H. Yamada and K. Terao, Phase Transitions, 2002, Vol. 75, No. 1–2, pp. 231–242. |