Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Quantum Liquids, Miscellaneous 1

TT 9.8: Talk

Monday, March 11, 2013, 11:30–11:45, H21

Fractional Chern insulator in the triangular lattice — •Stefanos Kourtis and Maria Daghofer — Leibniz Institute for Solid-State & Materials Research, Dresden, Germany

The formation of fractional quantum-Hall (FQH) states in lattice systems without externally applied magnetic fields is a recent and promising theoretical proposal that has the potential to render the FQH effect experimentally more accessible. Motivated by the emergence of the relevant physics in 3-orbital Hubbard and Kondo-lattice models on the triangular lattice [1,2], we study numerically an effective interacting spinless-fermion model and show that it yields spontaneously occurring FQH states, recently dubbed fractional Chern insulators (FCI). The Hall conductivity of these states is evaluated and shown to be fractionally quantized. This quantization is found to persist against disorder, demonstrating that the Hall conductivity is characterizing FCI states as a topological invariant. Having thus identified FCI states, we highlight further signatures of their nature in the obtained eigenvalue spectra and discuss the consequences of disorder and competition with conventional ordering.
[1] J.W.F. Venderbos, S. Kourtis, J. van den Brink, and M. Daghofer, Phys. Rev. Lett. 108, 126405
S. Kourtis, J.W.F. Venderbos, and M. Daghofer, arXiv:1208.3481