Enhancing the stability of a fractional Chern insulator against competing phases

Abstract

We construct a two-band lattice model whose bands can carry the Chern numbers C=0,pm1,pm2. By means of numerical exact diagonalization, we show that the most favorable situation that selects fractional Chern insulators (FCIs) is not necessarily the one that mimics Landau levels, namely a flat band with Chern number 1. First, we find that the gap, measured in units of the on-site electron-electron repulsion, can increase by almost two orders of magnitude when the bands are flat and carry a Chern number C=2 instead of C=1. Second, we show that giving a width to the bands can help to stabilize a FCI. Finally, we put forward a tool to characterize the real-space density profile of the ground state that is useful to distinguish FCI from other competing phases of matter supporting charge density waves or phase separation.

10 pages, 6 figures

References in corpus (8)

• Fractional quantum Hall states at zero magnetic field
• Fractional quantum Hall effect in the absence of Landau levels
• Fractional Chern Insulators in Topological Flat bands with Higher Chern Number
• Fractional Quantum Hall Effect in Topological Flat Bands with Chern Number Two
• Quantum Hall system in Tao-Thouless limit
• Half-Filled Lowest Landau Level on a Thin Torus
• One-Dimensional Theory of the Quantum Hall System
• Elementary formula for the Hall conductivity of interacting systems

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