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arXiv · 2507.11396

Large ferromagnetic-like band splitting in ultrathin ${\mathrm{SmC}}_{6}$ films

Hao Zheng·Yifu Xu·Guowei Yang·Ze Pan·Yi Wu·Yuan Zheng·Tulai Sun·Jiefeng Cao·Yi-feng Yang·Ming Shi·Chao Cao·Yang Liu
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Abstract

Two-dimensional (2D) magnetic materials provide a unique platform for exploring quantum phases from magnetic order in reduced dimensions. While there have been extensive studies on 2D magnetic materials based on 3$d$ electrons, experimental studies on 4$f$-electron counterparts are far fewer, particularly on their electronic structure. In this study, we report the successful synthesis of ultrathin ${\mathrm{SmC}}_{6}$ films using molecular beam epitaxy. Utilizing in situ angle-resolved photoemission spectroscopy (ARPES), we uncover a large band splitting in the valence bands, which we attribute to the ferromagnetic order driven by exchange couplings between Sm 4$f$ moments and conduction electrons. Despite the small magnetic moment of Sm, the observed splitting is comparable to those of Eu- and Gd-based systems with much larger local moments. Interestingly, the surface state also exhibits splitting with similar magnitude and can be eliminated by overannealing, while the valence bands with ferromagnetic-like splittings remain robust. Our work provides spectroscopic insight to understand the electronic origin of magnetic order in Sm-based compounds. Our study also offers a platform to study 2D magnetic materials based on 4$f$ electrons.

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Hao Zheng, Yifu Xu, Guowei Yang, Ze Pan, Yi Wu, Yuan Zheng, Tulai Sun, Jiefeng Cao, Yi-feng Yang, Ming Shi, Chao Cao, Yang Liu. 2025-07-15. Large ferromagnetic-like band splitting in ultrathin ${\mathrm{SmC}}_{6}$ films. https://doi.org/10.1103/54yx-p554

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