TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.15.4.148
TI  - Floquet fractional Chern insulators and competing phases in twisted bilayer graphene
PY  - 2023/10/10
UR  - https://scipost.org/SciPostPhys.15.4.148
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 15
IS  - 4
SP  - 148
A1  - Hu, Peng-Sheng
AU  - Zhou, Yi-Han
AU  - Liu, Zhao
AB  - We study the many-body physics in twisted bilayer graphene coupled to periodic driving of a circularly polarized light when electron-electron interactions are taken into account. In the limit of high driving frequency $\Omega$, we use Floquet theory to formulate the system by an effective static Hamiltonian truncated to the order of $\Omega^{-2}$, which consists of a single-electron part and the screened Coulomb interaction. We numerically simulate this effective Hamiltonian by extensive exact diagonalization in the parameter space spanned by the twist angle and the driving strength. Remarkably, in a wide region of the parameter space, we identify Floquet fractional Chern insulator states in the partially filled Floquet valence bands. We characterize these topologically ordered states by ground-state degeneracy, spectral flow, and entanglement spectrum. In regions of the parameter space where fractional Chern insulator states are absent, we find topologically trivial charge density waves and band-dispersion-induced Fermi liquids which strongly compete with fractional Chern insulator states.
ER  -

@Article{10.21468/SciPostPhys.15.4.148,
	title={{Floquet fractional Chern insulators and competing phases in twisted bilayer graphene}},
	author={Peng-Sheng Hu and Yi-Han Zhou and Zhao Liu},
	journal={SciPost Phys.},
	volume={15},
	pages={148},
	year={2023},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.15.4.148},
	url={https://scipost.org/10.21468/SciPostPhys.15.4.148},
}