Flat bands emerged from the embedded kagome lattice in two-dimensional Ge layer on ZrB₂(0001)

Chi-Cheng Lee^1*, Antoine Fleurence², Yukiko Yamada-Takamura², Taisuke Ozaki³

¹Department of Physics, Tamkang University, Tamsui, New Taipei 251301, Taiwan
²School of Materials Science, Japan Advanced Institute of Science and Technology (JAIST), Nomi, Ishikawa 923-1292, Japan
³Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan

* Presenter:Chi-Cheng Lee, email:cclee.physics@gmail.com

The kagome lattice is known for hosting a dispersion-less band, which is called the flat band, in the electronic band structure. We will show that such a flat band can also exist in a seemingly different structure, the bitriangular lattice. Interestingly, the underlying mechanism giving rise to the flat band in the bitriangular lattice can be proven to be exactly the same as that found for the kagome lattice.[1] Such findings will be demonstrated via a tight-binding model and first-principles calculations. Experimentally, we found that such a system can be realized in an epitaxial two-dimensional Ge layer on the zirconium diboride thin films.[2] The experimental and theoretical results will be discussed in details.

[1] Chi-Cheng Lee, Antoine Fleurence, Yukiko Yamada-Takamura, and Taisuke Ozaki, Phys. Rev. B 100, 045150 (2019).
[2] A. Fleurence, C.-C. Lee, R. Friedlein, Y. Fukaya, S. Yoshimoto, K. Mukai, H. Yamane, N. Kosugi, J. Yoshinobu, T. Ozaki, and Y. Yamada-Takamura, Phys. Rev. B 102, 201102(R) (2020).

Keywords: flat band, kagome lattice, 2d Ge layer