Energy minima and ordering in ferromagnets with quenched randomness
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866914095711649792 |
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| author | Garanin, D. A. |
| author_facet | Garanin, D. A. |
| contents | Energy minimization at T=0 and Monte Carlo simulations at T>0 have been performed for 2D and 3D random-field and random-anisotropy systems of up to 100 million classical spins. The main finding is that 3D random-anisotropy systems magnetically order on lowering temperature, contrary to the theoretical predictions based on the Imry-Ma argument. If random-anisotropy is stronger than the exchange, which can be the case in sintered materials, the system still orders but the magnetization is strongly reduced and there is a large spin-glass component in the spin state, the heat capacity having a cusp instead of a divergence. 3D random-field systems do not magnetically order on lowering temperature but rather freeze into the correlated spin-glass state. Here, although magnetized local energy minima have lower energies than non-magnetized ones, magnetic ordering is prevented by singularities pinned by the random field. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_02292 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Energy minima and ordering in ferromagnets with quenched randomness Garanin, D. A. Statistical Mechanics Energy minimization at T=0 and Monte Carlo simulations at T>0 have been performed for 2D and 3D random-field and random-anisotropy systems of up to 100 million classical spins. The main finding is that 3D random-anisotropy systems magnetically order on lowering temperature, contrary to the theoretical predictions based on the Imry-Ma argument. If random-anisotropy is stronger than the exchange, which can be the case in sintered materials, the system still orders but the magnetization is strongly reduced and there is a large spin-glass component in the spin state, the heat capacity having a cusp instead of a divergence. 3D random-field systems do not magnetically order on lowering temperature but rather freeze into the correlated spin-glass state. Here, although magnetized local energy minima have lower energies than non-magnetized ones, magnetic ordering is prevented by singularities pinned by the random field. |
| title | Energy minima and ordering in ferromagnets with quenched randomness |
| topic | Statistical Mechanics |
| url | https://arxiv.org/abs/2506.02292 |