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arXiv · 2004.10916

Experimental evidence of monolayer AlB$_2$ with symmetry-protected Dirac cones

Daiyu Geng·Kejun Yu·Shaosheng Yue·Jin Cao·Wenbin Li·Dashuai Ma·Chaoxi Cui·Masashi Arita·Shiv Kumar·Eike F. Schwier·Kenya Shimada·Peng Cheng·Lan Chen·Kehui Wu·Yugui Yao·Baojie Feng
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Abstract

Monolayer AlB$_2$ is composed of two atomic layers: honeycomb borophene and triangular aluminum. In contrast with the bulk phase, monolayer AlB$_2$ is predicted to be a superconductor with a high critical temperature. Here, we demonstrate that monolayer AlB$_2$ can be synthesized on Al(111) via molecular beam epitaxy. Our theoretical calculations revealed that the monolayer AlB$_2$ hosts several Dirac cones along the $\Gamma$--M and $\Gamma$--K directions; these Dirac cones are protected by crystal symmetries and are thus resistant to external perturbations. The extraordinary electronic structure of the monolayer AlB$_2$ was confirmed via angle-resolved photoemission spectroscopy measurements. These results are likely to stimulate further research interest to explore the exotic properties arising from the interplay of Dirac fermions and superconductivity in two-dimensional materials.

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Daiyu Geng, Kejun Yu, Shaosheng Yue, Jin Cao, Wenbin Li, Dashuai Ma, Chaoxi Cui, Masashi Arita, Shiv Kumar, Eike F. Schwier, Kenya Shimada, Peng Cheng, Lan Chen, Kehui Wu, Yugui Yao, Baojie Feng. 2020-04-23. Experimental evidence of monolayer AlB$_2$ with symmetry-protected Dirac cones. https://doi.org/10.1103/physrevb.101.161407

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