Unified Description of Spin-Lattice Coupling and Thermodynamics in the Pyrochlore Heisenberg Antiferromagnet
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| Main Authors: | , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866911494697910272 |
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| author | Gen, Masaki Suwa, Hidemaro Imajo, Shusaku Dong, Chao Ueda, Hiroaki Tachibana, Makoto Ikeda, Akihiko Kindo, Koichi Kohama, Yoshimitsu |
| author_facet | Gen, Masaki Suwa, Hidemaro Imajo, Shusaku Dong, Chao Ueda, Hiroaki Tachibana, Makoto Ikeda, Akihiko Kindo, Koichi Kohama, Yoshimitsu |
| contents | We study an extended model to describe the spin-lattice coupling, incorporating individual vibrations of bonds and atomic sites alongside distance-dependent exchange interactions. The proposed spin Hamiltonian can be effectively considered as an interpolation between two well-established minimum models, the bond-phonon model and the site-phonon model. The extended model, which treats bond phonons and site phonons on comparable footing, well reproduces successive field-induced phase transitions as well as the thermodynamic properties of a three-up-one-down state in the pyrochlore-lattice Heisenberg antiferromagnet, including negative thermal expansion, an enhanced magnetocaloric effect, and a sharp specific-heat peak. The present approach is broadly applicable to various spin models, providing a framework for identifying the primary phonon modes responsible for spin-lattice coupling and for understanding complex magnetic phase diagrams. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_13535 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unified Description of Spin-Lattice Coupling and Thermodynamics in the Pyrochlore Heisenberg Antiferromagnet Gen, Masaki Suwa, Hidemaro Imajo, Shusaku Dong, Chao Ueda, Hiroaki Tachibana, Makoto Ikeda, Akihiko Kindo, Koichi Kohama, Yoshimitsu Strongly Correlated Electrons Materials Science We study an extended model to describe the spin-lattice coupling, incorporating individual vibrations of bonds and atomic sites alongside distance-dependent exchange interactions. The proposed spin Hamiltonian can be effectively considered as an interpolation between two well-established minimum models, the bond-phonon model and the site-phonon model. The extended model, which treats bond phonons and site phonons on comparable footing, well reproduces successive field-induced phase transitions as well as the thermodynamic properties of a three-up-one-down state in the pyrochlore-lattice Heisenberg antiferromagnet, including negative thermal expansion, an enhanced magnetocaloric effect, and a sharp specific-heat peak. The present approach is broadly applicable to various spin models, providing a framework for identifying the primary phonon modes responsible for spin-lattice coupling and for understanding complex magnetic phase diagrams. |
| title | Unified Description of Spin-Lattice Coupling and Thermodynamics in the Pyrochlore Heisenberg Antiferromagnet |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2508.13535 |