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<p>We report on the structural, magnetic, and magnetocaloric properties of the multicomponent Er<sub>0.7</sub>R<sub>0.3</sub>(Fe<sub>0.125</sub>Co<sub>0.875</sub>)<sub>2</sub> compounds (R = Gd, Tb). Rietveld refinement of X-ray diffraction data confirms the formation of a C15-type Laves phase structure with Fd-3&#xa0;m symmetry. The effects of Gd and Tb substitution on the Curie temperature, saturation magnetization, and magnetic entropy change were investigated. All compounds exhibit a second-order magnetic phase transition. In contrast to the sharp magnetocaloric effect typically observed in ferromagnets, the present compounds display broadened MCE peaks. This anomalous behavior is attributed to the unique magnetic state of the R-ion sublattice, characterized by a “weak” magnetic order according to Belov’s classification. Consequently, the R-sublattices exhibit partial magnetic disorder up to the Curie temperature while retaining a substantial response to external magnetic fields. Alternatively, the formation of a sperimagnetic structure within the R-sublattices, induced by local electric field variations due to Fe-ion neighbors, might also contribute to the observed MCE behavior. Our findings show that these materials demonstrate reliable magnetocaloric performance across a broad temperature range, with their MCE properties being finely tunable through rare earth substitutions, thereby significantly expanding their potential applications.</p>

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Anomalous magnetocaloric behaviour and extended temperature range in Er0.7R0.3(Fe0.125Co0.875)2 multicomponent laves phase compounds

  • 期刊论文

  • 发表日期：

    2025年1月20日

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  • I. Chaaba,
  • R. M’nassri

摘要

We report on the structural, magnetic, and magnetocaloric properties of the multicomponent Er0.7R0.3(Fe0.125Co0.875)2 compounds (R = Gd, Tb). Rietveld refinement of X-ray diffraction data confirms the formation of a C15-type Laves phase structure with Fd-3 m symmetry. The effects of Gd and Tb substitution on the Curie temperature, saturation magnetization, and magnetic entropy change were investigated. All compounds exhibit a second-order magnetic phase transition. In contrast to the sharp magnetocaloric effect typically observed in ferromagnets, the present compounds display broadened MCE peaks. This anomalous behavior is attributed to the unique magnetic state of the R-ion sublattice, characterized by a “weak” magnetic order according to Belov’s classification. Consequently, the R-sublattices exhibit partial magnetic disorder up to the Curie temperature while retaining a substantial response to external magnetic fields. Alternatively, the formation of a sperimagnetic structure within the R-sublattices, induced by local electric field variations due to Fe-ion neighbors, might also contribute to the observed MCE behavior. Our findings show that these materials demonstrate reliable magnetocaloric performance across a broad temperature range, with their MCE properties being finely tunable through rare earth substitutions, thereby significantly expanding their potential applications.