Topological insulators and fractional quantum Hall effect on the ruby lattice

Department of Physics, The University of Texas at Austin, Austin, Texas 78712, USA(Dated: June 7, 2011)We study a tight-binding model on the two-dimensional ruby lattice. This lattice supports severaltypes of first and second neighbor spin-dependent hopping parameters in an s-band model thatpreserves time-reversal symmetry. We discuss the phase diagram of this model for various values ofthe hopping parameters and filling fractions, and note an interesting competition between spin-orbitterms that individually would drive the system to a Z