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arXiv · 2504.14821

Band-spin-valley coupled exciton physics in antiferromagnetic MnPS$_3$

Dan Wang·Haowei Chen·Yu Pang·Xiaolong Zou·Wenhui Duan
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Abstract

The introduction of intrinsic magnetic order in two-dimensional (2D) semiconductors offers great opportunities for investigating correlated excitonic phenomena. Here, we employ full-spinor GW plus Bethe-Salpeter equation methodology to reveal rich exciton physics in a prototypical 2D N\'{e}el-type antiferromagnetic semiconductor MnPS$_3$, enabled by the interplay among inverted dispersion of the second valence band, spin-valley coupling and magnetic order. The negative hole mass increases the reduced mass of the lowest-energy bright exciton, leading to exchange splitting enhancement of the bright exciton relative to band-edge dark exciton. Notably, such splitting couples with spontaneous valley polarization to generate distinct excitonic fine structure between $K$ and $-K$ valleys, which dictate distinct relaxation behaviors. Crucially, magnetic order transition from N\'{e}el antiferromagnetic to ferromagnetic state induces significant quasiparticle band structure reconstruction and excitonic transitions modification, with low-energy optical excitations being exclusively contributed by majority-spin channel. These findings establish 2D antiferromagnetic semiconductors as an intriguing platform to study band-spin-valley coupled exciton physics.

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Dan Wang, Haowei Chen, Yu Pang, Xiaolong Zou, Wenhui Duan. 2025-04-21. Band-spin-valley coupled exciton physics in antiferromagnetic MnPS$_3$. https://doi.org/10.1103/wbnk-ywn2

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