Magnetic properties and electronic structure of CeFe<inf>2−x</inf>Mn<inf>x</inf> and CeFe<inf>2</inf>Mn<inf>x</inf> compounds

The effect of manganese alloying on the structure and magnetic properties of CeFe2 has been studied on two isostructural series: quasibinary CeFe2−xMnx and nonstoichiometric CeFe2Mnx alloys. The single-phase bcc MgCu2-type structure is formed at x≤0.5 in both systems. At x=0.5, the lattice parameter is increased by ∼0.3%. The Mn alloying leads to a nonmonotonic variation of magnetic moment and gradual decrease in the Curie temperature from 230 K to 150 K and 167 K for CeFe1.5Mn0.5 and CeFe2Mn0.5, respectively. For x≥0.3, the magnetization data indicate the formation of noncollinear magnetic structure. The binary CeFe2 and nonstoichiometric CeFe2Mn0.15 have been studied using Mössbauer effect and X-ray photoelectron spectroscopy. The Ce valence state remains unchanged upon the Mn alloying. The parameters of hyperfine interactions have been determined in paramagnetic state at room temperature and in magnetically ordered state at 78 K. The Mössbauer data revealed a difference in the quadrupole coupling constants of CeFe2 and CeFe2Mn0.15, which is associated with the difference in the local distortions of the lattice