Fractional Chern insulators with strong interactions that far exceed band gaps.
We study two models for spinless fermions featuring topologically nontrivial bands characterized by Chern numbers C=±1 at fractional filling. Using exact diagonalization, we show that, even for infinitely strong nearest-neighbor repulsion, the ground states of these models belong to the recently discovered class of quantum liquids called fractional Chern insulators (FCI). Thus, we establish that FCI states can arise even if interaction strengths are arbitrarily larger than the noninteracting band gap, going beyond the limits in which FCI states have been previously studied. The strong-coupling FCI states, therefore, depart from the usual isolated-band picture that parallels the fractional quantum Hall effect in Landau levels and demonstrate how a topologically ordered state can arise in a truly multiband system.
Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.
Stefanos
S
Kourtis
Princeton Center for Theoretical Science, Princeton University, Princeton, New Jersey 08544, USA.
Titus
T
Neupert
Physics Department, Boston University, Boston, Massachusetts 02215, USA.
Claudio
C
Chamon
Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
Christopher
C
Mudry