تقرير
FeS2 monolayer: a high valence and high-$T_{\rm C}$ Ising ferromagnet
| العنوان: | FeS2 monolayer: a high valence and high-$T_{\rm C}$ Ising ferromagnet |
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| المؤلفون: | Yang, Ke, Ma, Yaozhenghang, Liu, Lu, Ning, Yueyue, Lu, Di, Zhou, Yuxuan, Li, Zhongyao, Wu, Hua |
| المصدر: | Phys. Rev. B 109, 014431 (2024) |
| سنة النشر: | 2024 |
| المجموعة: | Condensed Matter |
| مصطلحات موضوعية: | Condensed Matter - Materials Science |
| الوصف: | Two-dimensional (2D) magnetic materials are of current great interest for their promising applications in spintronics. Strong magnetic coupling and anisotropy are both highly desirable for the achievement of a high temperature magnetic order. Here we propose the unusual high valent FeS$_2$ hexagonal monolayer as such a candidate for a strong Ising 2D ferromagnet (FM), by spin-orbital state analyses, first-principles calculations, and the renormalized spin-wave theory (RSWT). We find that very importantly, the high valent Fe$^{4+}$ ion is in the low-spin state ($t_{2g}^{4}$, $S$=1) with degenerate $t_{2g}$ orbitals rather than the high-spin state ($t_{2g}^{3}e_g^{1}$, $S$=2). It is the low-spin state that allows to carry a large perpendicular orbital moment and then produces a huge single ion anisotropy (SIA) of 25 meV/Fe. Moreover, the negative charge transfer character associated with the unusual high valence, strong Fe $3d$-S $3p$ hybridization, wide bands, and a small band gap all help to establish a strong superexchange. Indeed, our first-principles calculations confirm the strong FM superexchange and the huge perpendicular SIA, both of which are further enhanced by a compressive strain. Then, our RSWT calculations predict that the FM $T_{\rm C}$ is 261 K for the pristine FeS$_2$ monolayer and could be increased to 409 K under the compressive --5\% strain. The high $T_{\rm C}$ is also reproduced by our Monte Carlo (MC) simulations. Therefore, it is worth exploring the high-$T_{\rm C}$ Ising FMs in the high valent 2D magnetic materials with degenerate orbitals. Comment: 13 pages, 5 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.1103/PhysRevB.109.014431 |
| URL الوصول: | http://arxiv.org/abs/2401.06357 |
| رقم الأكسشن: | edsarx.2401.06357 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.1103/PhysRevB.109.014431 |
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