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Charge imbalance and bilayer two-dimensional electron systems at nuT=1

Champagne, A. R. and Finck, A. D. K. and Eisenstein, J. P. and Pfeiffer, L. N. and West, K. W. (2008) Charge imbalance and bilayer two-dimensional electron systems at nuT=1. Physical Review B, 78 (20). Art. No. 205310. ISSN 1098-0121.

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We use interlayer tunneling to study bilayer two-dimensional electron systems at nuT=1 over a wide range of charge-density imbalance Deltanu=nu1−nu2 between the two layers. We find that the strongly enhanced tunneling associated with the coherent excitonic nuT=1 phase at small layer separation can survive at least up to an imbalance of Deltanu=0.5, i.e., (nu1,nu2)=(3/4,1/4). Phase transitions between the excitonic nuT=1 state and bilayer states which lack significant interlayer correlations can be induced in three different ways: by increasing the effective interlayer spacing d/[script-l], the temperature T, or the charge imbalance Deltanu. We observe that close to the phase boundary the coherent nuT=1 phase can be absent at Deltanu=0, present at intermediate Deltanu, and then absent again at large Deltanu, thus indicating an intricate phase competition between it and incoherent quasi-independent layer states. At zero imbalance, the critical d/[script-l] shifts linearly with temperature, while at Deltanu=1/3 the critical d/[script-l] is only weakly dependent on T. At Deltanu=1/3 we report on an observation of a direct phase transition between the coherent excitonic nuT=1 bilayer integer quantum Hall phase and the pair of single-layer fractional quantized Hall states at nu1=2/3 and nu2=1/3.

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Additional Information:© 2008 The American Physical Society. (Received 8 August 2008; published 10 November 2008) We are grateful to S. Das Sarma, A.H. MacDonald, E.H. Rezayi, X.G. Wen, K. Yang, and especially to G. Refael for discussions and to I.B. Spielman for technical help. This work was supported by the NSF under Grant No. DMR-0552270 and the DOE under Grant No. DE-FG03-99ER45766.
Funding AgencyGrant Number
National Science FoundationMR-0552270
Department of EnergyDE-FG03-99ER45766
Subject Keywords:aluminum compounds; charge density waves; excitons; gallium arsenide; gallium compounds; III-V semiconductors; semiconductor heterojunctions; semiconductor quantum wells; tunnelling
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12391
Deposited By: Archive Administrator
Deposited On:15 Nov 2008 01:02
Last Modified:26 Dec 2012 10:31

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