2008/08/31 by A. R. Champagne, A. D. K. Finck, J. P. Eisenstein +2 · 2 citations
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Semiconductor Quantum Structures and Devices #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.78.205310
published as Phys. Rev. B 78, 205310 (2008) · 13 pages, 8 postscript figures. Final published version
openalex publication_date 2008/11/10 · arxiv created 2008/11/19 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/04
We use interlayer tunneling to study bilayer two-dimensional electron systems at \ensuremathνT=1 over a wide range of charge-density imbalance \ensuremathΔ\ensuremathν=\ensuremathν1\ensuremath-\ensuremathν2 between the two layers. We find that the strongly enhanced tunneling associated with the coherent excitonic \ensuremathνT=1 phase at small layer separation can survive at least up to an imbalance of \ensuremathΔ\ensuremathν=0.5, i.e., (\ensuremathν1,\ensuremathν2)=(3/4,1/4). Phase transitions between the excitonic \ensuremathνT=1 state and bilayer states which lack significant interlayer correlations can be induced in three different ways: by increasing the effective interlayer spacing d/\ensuremathℓ, the temperature T, or the charge imbalance \ensuremathΔ\ensuremathν. We observe that close to the phase boundary the coherent \ensuremathνT=1 phase can be absent at \ensuremathΔ\ensuremathν=0, present at intermediate \ensuremathΔ\ensuremathν, and then absent again at large \ensuremathΔ\ensuremathν, thus indicating an intricate phase competition between it and incoherent quasi-independent layer states. At zero imbalance, the critical d/\ensuremathℓ shifts linearly with temperature, while at \ensuremathΔ\ensuremathν=1/3 the critical d/\ensuremathℓ is only weakly dependent on T. At \ensuremathΔ\ensuremathν=1/3 we report on an observation of a direct phase transition between the coherent excitonic \ensuremathνT=1 bilayer integer quantum Hall phase and the pair of single-layer fractional quantized Hall states at \ensuremathν1=2/3 and \ensuremathν2=1/3.