Numerical Study of Quantum Hall Bilayers at Total Filling ν_{T}=1 : A New Phase at Intermediate Layer Distances
Abstract
We study the phase diagram of quantum Hall bilayer systems with total filing ν_{T}=1 /2 +1 /2 of the lowest Landau level as a function of layer distances d . Based on numerical exact diagonalization calculations, we obtain three distinct phases, including an exciton superfluid phase with spontaneous interlayer coherence at small d , a composite Fermi liquid at large d , and an intermediate phase for 1.1 <d /l_{B}<1.8 (l_{B} is the magnetic length). The transition from the exciton superfluid to the intermediate phase is identified by (i) a dramatic change in the Berry curvature of the ground state under twisted boundary conditions on the two layers and (ii) an energy level crossing of the first excited state. The transition from the intermediate phase to the composite Fermi liquid is identified by the vanishing of the exciton superfluid stiffness. Furthermore, from our finitesize study, the energy cost of transferring one electron between the layers shows an evenodd effect and possibly extrapolates to a finite value in the thermodynamic limit, indicating the enhanced intralayer correlation. Our identification of an intermediate phase and its distinctive features shed new light on the theoretical understanding of the quantum Hall bilayer system at total filling ν_{T}=1 .
 Publication:

Physical Review Letters
 Pub Date:
 October 2017
 DOI:
 10.1103/PhysRevLett.119.177601
 arXiv:
 arXiv:1703.08463
 Bibcode:
 2017PhRvL.119q7601Z
 Keywords:

 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 5 pages, 3 figures (main text)