Article Magnetic correlations and crystal structure changes in Fe- and Ni-substituted ErCo2 with reversible giant magnetocaloric effect

Simon Rosenqvist Larsen ORCID ; Noriki Terada SAMURAI ORCID ; Xin Tang SAMURAI ORCID ; Hiroaki Mamiya ; Yusuke Nambu ORCID ; Daisuke Okuyama ORCID ; Hossein Sepehri-Amin SAMURAI ORCID

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Simon Rosenqvist Larsen, Noriki Terada, Xin Tang, Hiroaki Mamiya, Yusuke Nambu, Daisuke Okuyama, Hossein Sepehri-Amin. Magnetic correlations and crystal structure changes in Fe- and Ni-substituted ErCo2 with reversible giant magnetocaloric effect. Physical Review B. 2025, 112 (1), 014443. https://doi.org/10.1103/6lt2-4pwb

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(abstract)

In this study the microscopic magnetic correlations and crystal lattice distortions are investigated by neutron and synchrotron X-ray diffraction, as well as AC susceptibility measurements. The results indicated that in contrast to the previous study, the cu- bic to rhombohedral structure change was not suppressed, though the way the unit cell expansion occurred did change. No significant changes were observed in the magnetic long range order and crystal lattice symmetry, which still formed a ferrimagnetic and rhombohedral crystal structure below the phase transition temperature (TC) for all substitutions as well as pure ErCo2. However, an increase in magnetic short range correlations above TC, which is strongly correlated with the entropy change and the dynamic AC susceptibility, was detected only in the substituted samples. Unlike pure ErCo2, the nucleation of the local ferrimagnetic clusters above TC occurs in the sub- stituted samples, which significantly reduces the energy barrier between the higher temperature cubic phase and the lower temperature rhombohedral phase. It is concluded that the reduction of the energy barrier due to the development of short range order induced by chemical substitution at temperatures above TC is possibly the origin of the significant change in the nature of the phase transition in ErCo2.

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Keyword: magnetocaloric effect, neutron diffraction

Date published: 2025-07-23

Publisher: American Physical Society (APS)

Journal:

  • Physical Review B (ISSN: 24699950) vol. 112 issue. 1 014443

Funding:

  • Japan Society for the Promotion of Science 22H00297
  • Japan Society for the Promotion of Science JP24K00572
  • Japan Society for the Promotion of Science JP22H05145
  • Japan Society for the Promotion of Science JPJSJRP20221608
  • Japan Science and Technology Agency JPMJFR202V
  • National Institute for Materials Science

Manuscript type: Author's version (Accepted manuscript)

MDR DOI: https://doi.org/10.48505/nims.5614

First published URL: https://doi.org/10.1103/6lt2-4pwb

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Updated at: 2025-07-30 08:30:20 +0900

Published on MDR: 2025-07-30 08:16:41 +0900

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