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Several spinless-fermion models featuring topologically non-trivial and flat bands have been recently studied as a potential host of lattice fractional quantum-Hall (FQH) states in the absence of a magnetic field, dubbed fractional Chern insulators (FCI). We introduce such an effective model on the triangular lattice including short-range interactions, originally derived from a 3-orbital model describing layered transition-metal oxides [1,2], and study its ground states as a function of filling, interaction strength and band dispersion using exact diagonalization [3]. Using symmetry arguments as well as appropriate observables, such as the Hall conductivity and the static charge-structure factor, we identify FCI and charge-density wave (CDW) ground states at various filling fractions and trace the phase diagram of the model for some of these fillings. We show that FCI states survive the competition against CDW states for a wide parameter range and that they remain robust against disorder in the magnetic background. We also compare to similar results obtained for a checkerboard-lattice model [4].
[1] J.W.F. Venderbos, M. Daghofer, and J. van den Brink, Phys. Rev. Lett. 107, 116401 (2011). [2] J.W.F. Venderbos, S. Kourtis, J. van den Brink, and M. Daghofer, Phys. Rev. Lett. 108, 126405 (2012). [3] S. Kourtis, J.W.F. Venderbos, and M. Daghofer, Phys. Rev. B 86, 235118 (2012). [4] K. Sun, Z. Gu, H. Katsura, and S. Das Sarma, Phys. Rev. Lett. 106, 236803 (2011) |
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