Topological insulators on the square–hexagon lattice driven by next-nearest-neighbor hopping. (6th July 2022)

• Record Type: Journal Article
• Authors: Wang, Guo Xiang; Zhang, Ying Zheng; Wei, Jun Hong
• Is Part Of: Journal of physics. Volume 34:Number 27(2022)
• Publication Date: 2022-07-06
• Subjects: square–hexagon lattice -- tight-binding model -- topological phase transition; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/ac6788
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We investigate the topological phase transition of the square–hexagon lattice driven by the next-nearest-neighbor (NNN) hopping. By means of the Fukui–Hatsugai method, the topological invariant Z 2 can be determined. The phase diagrams in the ( t 1, t 2 ) plane for different filling fractions are displayed, together with the size of the bulk band gap. We find the competition between t 1 and t 2 can drive the system into topological nontrivial phase, with Z 2 = 1. Interestingly, for 2/5 and 3/5 filling fractions, topological nontrivial phase can be easily realized when the NNN hoppings are turned on. Besides, the phase diagrams in the plane of t 2 and λ so 2 ( t 1 and λ so 1 ) are also investigated. By numerically diagonalizing the Hamiltonian, the bulk band structures are calculated. And the topological trivial and nontrivial phase are also distinguished in terms of helical edge state. In experiments, these topological phase transitions may be realized by shaking optical lattice.