Direct observation of the Mottness and p-d orbital hybridization in the epitaxial monolayer α-RuCl3

Zhongjie Wang; Lu Liu; Haoran Zheng; Meng Zhao; Ke Yang; Chunzheng Wang; Fang Yang; Hua Wu; Chunlei Gao

doi:10.1039/d2nr02827a

Direct observation of the Mottness and p-d orbital hybridization in the epitaxial monolayer α-RuCl₃

Nanoscale. 2022 Aug 18;14(32):11745-11749. doi: 10.1039/d2nr02827a.

Authors

Zhongjie Wang¹, Lu Liu^{1

2}, Haoran Zheng¹, Meng Zhao¹, Ke Yang^{1

2}, Chunzheng Wang¹, Fang Yang^{3

4}, Hua Wu^{1

2

5

6}, Chunlei Gao^{1

3

4

5

6

7}

Affiliations

¹ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200438, China. wuh@fudan.edu.cn.
² Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200438, China.
³ Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Songhu Rd. 2005, Shanghai 200438, China.
⁴ Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 201210, China.
⁵ Shanghai Qi Zhi Institute, Shanghai 200232, China.
⁶ Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.
⁷ Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.

PMID: 35917194
DOI: 10.1039/d2nr02827a

Abstract

α-RuCl₃, a promising material to accomplish the Kitaev honeycomb model, has attracted enormous interest recently. Mottness and p-d bonds play vital roles in generating Kitaev interactions and underpinning the potential exotic states of quantum magnets, and the van der Waals monolayer is considered to be a better platform to approach a two-dimensional Kitaev model than the bulk. Here, we worked out the growth art of an α-RuCl₃ monolayer on a graphite substrate and studied its electronic structure, particularly the delicate orbital occupations, through scanning tunneling microscopy and spectroscopy. An in-plane lattice expansion of 2.67 ± 0.83% is observed and the pronounced t_2g-p_π and e_g-p_σ hybridization are visualized. The Mott nature is unveiled by an ∼0.6 eV full gap at the Fermi level located inside the t_2g-p_π manifold which is further verified by the density functional theory calculations. The monolayer phase of α-RuCl₃ fulfills the a priori criteria of recent theoretical predictions of tuning the relevant properties in this material and provides a novel platform to explore the Kitaev physics.