Coexistence of Composite Bosons and Composite Fermions in nu=1/2 + 1/2 Quantum Hall Bilayers.
25 July 2003
In bilayer quantum Hall systems at filling fractions near $nu=1/2+1/2$, as the spacing $d$ between the layers is continuously decreased, intra-layer correlations must be replaced by inter-layer correlations, and the composite fermion (CF) Fermi seas at large $d$ must eventually be replaced by a composite boson (CB) condensate or ``111 state" at small $d$.
We propose a scenario where CBs and CFs coexist in two interpenetrating fluids in the transition. Trial wavefunctions describing these mixed CB-CF states compare very favorably with exact diagonalization results. A Chern-Simons transport theory is constructed that is compatible with experiment