Spin ice in a general applied magnetic field: Kasteleyn transition, magnetic torque and rotational magnetocaloric effect
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arXiv
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| Auteurs principaux: | , |
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| Format: | Preprint |
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2022
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| _version_ | 1866907925481521152 |
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| author | Potts, Mark Benton, Owen |
| author_facet | Potts, Mark Benton, Owen |
| contents | Spin ice is a paradigmatic frustrated system famous for the emergence of magnetic monopoles and a large magnetic entropy at low temperatures. It exhibits unusual behavior in the presence of an external magnetic field as a result of the competition between the spin ice entropy and the Zeeman energy. Studies of this have generally focused on fields applied along high symmetry directions: [111], [001], and [110]. Here we consider a model of spin ice with external field in an arbitrary direction. We find that the Kasteleyn transition known for $[001]$ fields, appears also for general field directions and calculate the associated Kasteleyn temperature $T_K$ as a function of field direction. $T_K$ is found to vanish, with a logarithmic dependence on field angle, approaching certain lines of special field directions. We further investigate the thermodynamic properties of spin ice for $T>T_K$, using a Husimi cactus approximation. As the system is cooled towards $T_K$ a large magnetic torque appears, tending to align the $[001]$ crystal axis with the external field. The model also exhibits a rotational magnetocaloric effect: significant temperature changes can be obtained by adabiatically rotating the crystal relative to a fixed field. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2204_01575 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | Spin ice in a general applied magnetic field: Kasteleyn transition, magnetic torque and rotational magnetocaloric effect Potts, Mark Benton, Owen Strongly Correlated Electrons Statistical Mechanics Spin ice is a paradigmatic frustrated system famous for the emergence of magnetic monopoles and a large magnetic entropy at low temperatures. It exhibits unusual behavior in the presence of an external magnetic field as a result of the competition between the spin ice entropy and the Zeeman energy. Studies of this have generally focused on fields applied along high symmetry directions: [111], [001], and [110]. Here we consider a model of spin ice with external field in an arbitrary direction. We find that the Kasteleyn transition known for $[001]$ fields, appears also for general field directions and calculate the associated Kasteleyn temperature $T_K$ as a function of field direction. $T_K$ is found to vanish, with a logarithmic dependence on field angle, approaching certain lines of special field directions. We further investigate the thermodynamic properties of spin ice for $T>T_K$, using a Husimi cactus approximation. As the system is cooled towards $T_K$ a large magnetic torque appears, tending to align the $[001]$ crystal axis with the external field. The model also exhibits a rotational magnetocaloric effect: significant temperature changes can be obtained by adabiatically rotating the crystal relative to a fixed field. |
| title | Spin ice in a general applied magnetic field: Kasteleyn transition, magnetic torque and rotational magnetocaloric effect |
| topic | Strongly Correlated Electrons Statistical Mechanics |
| url | https://arxiv.org/abs/2204.01575 |