Octupolar vortex crystal and toroidal moment in twisted bilayer MnPSe$_3$
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| Format: | Preprint |
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2024
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| _version_ | 1866912107628331008 |
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| author | Akram, Muhammad Yang, Fan Birol, Turan Erten, Onur |
| author_facet | Akram, Muhammad Yang, Fan Birol, Turan Erten, Onur |
| contents | Experimental detection of antiferromagnetic order in two-dimensional materials is a challenging task due to the absence of net dipole moments. Identifying multi-domain antiferromagnetic textures via the current techniques is even more difficult. In order to address this challenge, we investigate the higher order multipole moments in twisted bilayer MnPSe$_3$. While the monolayers of MnPSe$_3$ exhibit in-plane Néel antiferromagnetic order, our atomistic simulations indicate that the moiré superlattices display a two-domain phase on each layer. We show that the octupolar moments $M_{33}^+$ and $M_{33}^-$ are significant in this multi-domain phase at the domain walls. In addition, when $[M_{33}^+,M_{33}^-]$ are represented by the $x$ and $y$ components of a vector, the resultant pattern of these octupole moments winds around the antiferromagnetic domains and forms to vortex crystals which leads to octupolar toroidal moments, $T_{xyz}$ and $T_{z}^β$. $T_{xyz}$ and $T_{z}^β$ can give rise to a magnetoelectric effect and gyrotropic birefringence that may provide indirect ways of detecting multi-domain antiferromagnetic order. Our results highlight the importance of higher-order multipole moments for identification of complex spin textures in moiré magnets. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2411_04117 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Octupolar vortex crystal and toroidal moment in twisted bilayer MnPSe$_3$ Akram, Muhammad Yang, Fan Birol, Turan Erten, Onur Strongly Correlated Electrons Materials Science Experimental detection of antiferromagnetic order in two-dimensional materials is a challenging task due to the absence of net dipole moments. Identifying multi-domain antiferromagnetic textures via the current techniques is even more difficult. In order to address this challenge, we investigate the higher order multipole moments in twisted bilayer MnPSe$_3$. While the monolayers of MnPSe$_3$ exhibit in-plane Néel antiferromagnetic order, our atomistic simulations indicate that the moiré superlattices display a two-domain phase on each layer. We show that the octupolar moments $M_{33}^+$ and $M_{33}^-$ are significant in this multi-domain phase at the domain walls. In addition, when $[M_{33}^+,M_{33}^-]$ are represented by the $x$ and $y$ components of a vector, the resultant pattern of these octupole moments winds around the antiferromagnetic domains and forms to vortex crystals which leads to octupolar toroidal moments, $T_{xyz}$ and $T_{z}^β$. $T_{xyz}$ and $T_{z}^β$ can give rise to a magnetoelectric effect and gyrotropic birefringence that may provide indirect ways of detecting multi-domain antiferromagnetic order. Our results highlight the importance of higher-order multipole moments for identification of complex spin textures in moiré magnets. |
| title | Octupolar vortex crystal and toroidal moment in twisted bilayer MnPSe$_3$ |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2411.04117 |