Anomalous magnetic response in the Au-Al-Gd 1/1 quasicrystal approximant
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arXiv
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| Main Authors: | , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866916800033193984 |
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| author | Yamamoto, Takafumi D. Watanae, Tasuku Labib, Farid Ishikawa, Asuka Suzuki, Shintaro Tamura, Ryuji |
| author_facet | Yamamoto, Takafumi D. Watanae, Tasuku Labib, Farid Ishikawa, Asuka Suzuki, Shintaro Tamura, Ryuji |
| contents | The magnetic response of the Tsai-type 1/1 Au-Al-Gd approximant crystals (ACs) was quantitatively investigated in terms of the magnetic entropy change ($ΔS_{M}$) for different magnetic ground states. A comprehensive $ΔS_{M}$ map over a wide electron concentration range has been established, demonstrating the detailed variation of $ΔS_{M}$ across the entire magnetic phase diagram in the Tsai-type 1/1 ACs. Near the boundaries of the ferromagnetic (FM) phase, a clear deviation from the mean-field theory (MFT) was observed in both the Curie temperature ($T_{C}$) and magnetic field ($H$) dependences of the maximum magnetic entropy change ($ΔS_{M}^{max}$). Contrary to general expectations, a high $ΔS_{M}^{max}$ (7.2 J/K mol-Gd under a 5 T field variation), even comparable to those of candidate materials for low-temperature magnetic refrigeration, was obtained within the antiferromagnetic (AFM) region near the FM / AFM phase boundary. The unexpected enhancement of $ΔS_{M}^{max}$ toward the AFM region under high magnetic fields indicates an anomalous magnetic response in the present Tsai-type 1/1 AC, which is presumably associated with the breakdown of the MFT. The present finding suggests that tuning the magnetic ground state across the phase boundary is an effective strategy to enhance $ΔS_{M}$, even in general rare-earth intermetallic compounds. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_00778 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Anomalous magnetic response in the Au-Al-Gd 1/1 quasicrystal approximant Yamamoto, Takafumi D. Watanae, Tasuku Labib, Farid Ishikawa, Asuka Suzuki, Shintaro Tamura, Ryuji Materials Science Strongly Correlated Electrons The magnetic response of the Tsai-type 1/1 Au-Al-Gd approximant crystals (ACs) was quantitatively investigated in terms of the magnetic entropy change ($ΔS_{M}$) for different magnetic ground states. A comprehensive $ΔS_{M}$ map over a wide electron concentration range has been established, demonstrating the detailed variation of $ΔS_{M}$ across the entire magnetic phase diagram in the Tsai-type 1/1 ACs. Near the boundaries of the ferromagnetic (FM) phase, a clear deviation from the mean-field theory (MFT) was observed in both the Curie temperature ($T_{C}$) and magnetic field ($H$) dependences of the maximum magnetic entropy change ($ΔS_{M}^{max}$). Contrary to general expectations, a high $ΔS_{M}^{max}$ (7.2 J/K mol-Gd under a 5 T field variation), even comparable to those of candidate materials for low-temperature magnetic refrigeration, was obtained within the antiferromagnetic (AFM) region near the FM / AFM phase boundary. The unexpected enhancement of $ΔS_{M}^{max}$ toward the AFM region under high magnetic fields indicates an anomalous magnetic response in the present Tsai-type 1/1 AC, which is presumably associated with the breakdown of the MFT. The present finding suggests that tuning the magnetic ground state across the phase boundary is an effective strategy to enhance $ΔS_{M}$, even in general rare-earth intermetallic compounds. |
| title | Anomalous magnetic response in the Au-Al-Gd 1/1 quasicrystal approximant |
| topic | Materials Science Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2506.00778 |