Hierarchy of fractional Chern insulators and competing compressible states

Abstract

We study the phase diagram of interacting electrons in a dispersionless Chern band as a function of their filling. We find hierarchy multiplets of incompressible states at fillings ν=1/3, 2/5, 3/7, 4/9, 5/9, 4/7, 3/5 as well as ν=1/5,2/7. These are accounted for by an analogy to Haldane pseudopotentials extracted from an analysis of the two-particle problem. Important distinctions to standard fractional quantum Hall physics are striking: absent particle-hole symmetry in a single band, an interaction-induced single-hole dispersion appears, which perturbs and eventually destabilizes incompressible states as νincreases. For this reason the nature of the state at ν=2/3 is hard to pin down, while ν=5/7,4/5 do not seem to be incompressible in our system.

5 pages with 4 figures, plus 6 pages and 8 figures of supplementary material