Contrasting magnetism in VPS3 and CrI3 monolayers with the common honeycomb S = 3/2 spin lattice
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2025
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| _version_ | 1866917986608087040 |
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| author | Yang, Ke Ning, Yueyue Ma, Yaozhenghang Zhou, Yuxuan Wu, Hua |
| author_facet | Yang, Ke Ning, Yueyue Ma, Yaozhenghang Zhou, Yuxuan Wu, Hua |
| contents | Two-dimensional (2D) magnetic materials are promising candidates for spintronics and quantum technologies. One extensively studied example is the ferromagnetic (FM) CrI$_3$ monolayer with the honeycomb Cr$^{3+}$ ($t_{2g}^3$, $S$ = 3/2) spin lattice, while VPS$_3$ has a same honeycomb $S$ = 3/2 spin lattice (V$^{2+}$, $t_{2g}^3$) but displays N$\acute{e}$el antiferromagnetism (AFM). In this work, we study the electronic structure and particularly the contrasting magnetism of VPS$_3$ and CrI$_3$ monolayers. We find that VPS$_3$ is a Mott-Hubbard insulator but CrI$_3$ is a charge-transfer insulator, and therefore their magnetic exchange mechanisms are essentially different. The first nearest-neighbor (1NN) direct $d$-$d$ exchange dominates in VPS$_3$, thus leading to a strong antiferromagnetic (AF) coupling. However, the formation of vanadium vacancies, associated with instability of the low-valence V$^{2+}$ ions, suppresses the AF coupling and thus strongly reduces the N$\acute{e}$el temperature ($T_{\text{N}}$) in line with the experimental observation. In contrast, our results reveal that the major 1NN $d$-$p$-$d$ superexchanges in CrI$_3$ via different channels give rise to competing FM and AF couplings, ultimately resulting in a weak FM coupling as observed experimentally. After revisiting several important superexchange channels reported in the literature, based on our MLWFs and tight-binding analyses, we note that some antiphase contributions must be subtly and simultaneously considered, and thus we provide a deeper insight into the FM coupling of CrI$_3$. Moreover, we identify and compare the major contributions to the magnetic anisotropy, i.e., a weak shape anisotropy in VPS$_3$ and a relatively strong exchange anisotropy in CrI$_3$. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2504_05952 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Contrasting magnetism in VPS3 and CrI3 monolayers with the common honeycomb S = 3/2 spin lattice Yang, Ke Ning, Yueyue Ma, Yaozhenghang Zhou, Yuxuan Wu, Hua Materials Science Two-dimensional (2D) magnetic materials are promising candidates for spintronics and quantum technologies. One extensively studied example is the ferromagnetic (FM) CrI$_3$ monolayer with the honeycomb Cr$^{3+}$ ($t_{2g}^3$, $S$ = 3/2) spin lattice, while VPS$_3$ has a same honeycomb $S$ = 3/2 spin lattice (V$^{2+}$, $t_{2g}^3$) but displays N$\acute{e}$el antiferromagnetism (AFM). In this work, we study the electronic structure and particularly the contrasting magnetism of VPS$_3$ and CrI$_3$ monolayers. We find that VPS$_3$ is a Mott-Hubbard insulator but CrI$_3$ is a charge-transfer insulator, and therefore their magnetic exchange mechanisms are essentially different. The first nearest-neighbor (1NN) direct $d$-$d$ exchange dominates in VPS$_3$, thus leading to a strong antiferromagnetic (AF) coupling. However, the formation of vanadium vacancies, associated with instability of the low-valence V$^{2+}$ ions, suppresses the AF coupling and thus strongly reduces the N$\acute{e}$el temperature ($T_{\text{N}}$) in line with the experimental observation. In contrast, our results reveal that the major 1NN $d$-$p$-$d$ superexchanges in CrI$_3$ via different channels give rise to competing FM and AF couplings, ultimately resulting in a weak FM coupling as observed experimentally. After revisiting several important superexchange channels reported in the literature, based on our MLWFs and tight-binding analyses, we note that some antiphase contributions must be subtly and simultaneously considered, and thus we provide a deeper insight into the FM coupling of CrI$_3$. Moreover, we identify and compare the major contributions to the magnetic anisotropy, i.e., a weak shape anisotropy in VPS$_3$ and a relatively strong exchange anisotropy in CrI$_3$. |
| title | Contrasting magnetism in VPS3 and CrI3 monolayers with the common honeycomb S = 3/2 spin lattice |
| topic | Materials Science |
| url | https://arxiv.org/abs/2504.05952 |