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arXiv · 2407.09153

Topological Fermi-arc surface state covered by floating electrons on a two-dimensional electride

Chan-young Lim·Min-Seok Kim·Dong Cheol Lim·Sunghun Kim·Yeonghoon Lee·Jaehoon Cha·Gyubin Lee·Sang Yong Song·Dinesh Thapa·Jonathan D. Denlinger·Seong-Gon Kim·Sung Wng Kim·Jungpil Seo·Yeongkwan Kim
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Abstract

Two-dimensional electrides can acquire topologically non-trivial phases due to intriguing interplay between the cationic atomic layers and anionic electron layers. However, experimental evidence of topological surface states has yet to be verified. Here, via angle-resolved photoemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM), we probe the magnetic Weyl states of the ferromagnetic electride $[Gd_{2}$C]^{2+}\cdot2e^{-}$. In particular, the presence of Weyl cones and Fermi-arc states is demonstrated through photon energy-dependent ARPES measurements, agreeing with theoretical band structure calculations. Notably, the STM measurements reveal that the Fermi-arc states exist underneath a floating quantum electron liquid on the top Gd layer, forming double-stacked surface states in a heterostructure. Our work thus not only unveils the non-trivial topology of the $[Gd_{2}$C]^{2+}\cdot2e^{-}$ electride but also realizes a surface heterostructure that can host phenomena distinct from the bulk.

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Chan-young Lim, Min-Seok Kim, Dong Cheol Lim, Sunghun Kim, Yeonghoon Lee, Jaehoon Cha, Gyubin Lee, Sang Yong Song, Dinesh Thapa, Jonathan D. Denlinger, Seong-Gon Kim, Sung Wng Kim, Jungpil Seo, Yeongkwan Kim. 2024-07-12. Topological Fermi-arc surface state covered by floating electrons on a two-dimensional electride. https://doi.org/10.1038/s41467-024-49841-6

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