Moment variation in Er(Co1−xFex)2 Laves phase: Magnetic measurements and Mössbauer spectroscopy study

Abstract

Er͑Co 1−x Fe x ͒ 2 cubic Laves phases have been studied by magnetic measurements and 57 Fe Mössbauer spectroscopy. With increasing x from 0 to 0.8, the magnetization decreases from 6.8 to 4.8 B / f.u. ͑5 K͒, then it slightly increases to 5.2 B / f.u. as x increases from 0.8 to 1.0. Assuming a fixed Er moment of 9 B ͑Er metal value͒, the corresponding moment of Co͑Fe͒ shows a maximum at x = 0.8 due to the antiparallel coupling between the Er and Co͑Fe͒ sublattices in the compounds. The 57 Fe spectra can be analyzed in terms of two distinct six-line 57 Fe patterns with intensities in the ratio of 1:3, indicating that the easy magnetization direction is along ͓111͔ in these compounds. The Fe content dependence of the hyperfine fields at the 57 Fe nuclei in Er͑Co 1−x Fe x ͒ 2 shows the same tendency as that of the moment variation of Co͑Fe͒, following a 3d-type Slater-Pauling dependence.

Features of Magnetocaloric Effect in Er(Co-Fe)2 Laves Phases

“…Taking into account the results of [5][6][7], it is possible to infer that the nonlinear T C (x) dependences correlate with the mean magnetic moment of the 3d-ions subsystem (x) in these compounds. Non-monotonic dependence T C (x) is correlated with the dependence of the magnetic moment of the d-sublattice vs. concentration iron (x).…”