Quantum Hall exciton condensation at full spin polarization.
Using Coulomb drag as a probe, we explore the excitonic phase transition in quantum Hall bilayers at nu(T) = 1 as a function of Zeeman energy E(Z). The critical layer separation (d/l)(c) for exciton condensation initially increases rapidly with E(Z), but then reaches a maximum and begins a gentle decline. At high E(Z), where both the excitonic phase at small d/l and the compressible phase at large d/l are fully spin polarized, we find that the width of the transition, as a function of d/l, is much larger than at small E(Z) and persists in the limit of zero temperature. We discuss these results in the context of two models in which the system contains a mixture of the two fluids.
Finck
A D K
AD
Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125, USA.
Eisenstein
J P
JP
Pfeiffer
L N
LN
West
K W
KW