Charge Imbalance and Bilayer 2D Electron Systems at ${\nu }_T=1$

Abstract

We use interlayer tunneling to study bilayer 2D electron systems at ${\nu }_T=1$ over a wide range of charge density imbalance, $\Delta \nu ={\nu }_1-{\nu }_2$, between the two layers. We find that the strongly enhanced tunneling associated with the coherent excitonic ${\nu }_T=1$ phase at small layer separation can survive at least up to an imbalance of $\Delta \nu$ = 0.5, i.e $({\nu }_1,{\nu }_2)$ = (3/4, 1/4). Phase transitions between the excitonic ${\nu }_T=1$ state and bilayer states which lack significant interlayer correlations can be induced in three different ways: by increasing the effective interlayer spacing $d/\ell$, the temperature $T$, or the charge imbalance, $\Delta \nu$. We observe that close to the phase boundary the coherent ${\nu }_T=1$ phase can be absent at $\Delta \nu$ = 0, present at intermediate $\Delta \nu$, but then absent again at large $\Delta \nu$, thus indicating an intricate phase competition between it and incoherent quasi-independent layer states. At zero imbalance, the critical $d/\ell$ shifts linearly with temperature, while at $\Delta \nu$ = 1/3 the critical $d/\ell$ is only weakly dependent on $T$. At $\Delta \nu$ = 1/3 we report the first observation of a direct phase transition between the coherent excitonic ${\nu }_T=1$ bilayer integer quantum Hall phase and the pair of single layer fractional quantized Hall states at ${\nu }_1$ = 2/3 and ${\nu }_2=1/3$.

13 pages, 8 postscript figures. Final published version

References in corpus (19)

• Bose-Einstein Condensation of Excitons in Bilayer Electron Systems
• Spontaneous Inter-layer Coherence in Double-Layer Quantum-Hall Systems I: Charged Vortices and Kosterlitz-Thouless Phase Transitions
• Evidence for a Goldstone Mode in a Double Layer Quantum Hall System
• Counterflow measurements in strongly correlated GaAs hole bilayers: evidence for electron-hole pairing
• Vanishing Hall Resistance at High Magnetic Field in a Double Layer Two-Dimensional Electron System
• Quantum Ferromagnetism and Phase Transitions in Double-Layer Quantum Hall Systems
• Observation of Quantized Hall Drag in a Strongly Correlated Bilayer Electron System
• Activated Transport in the individual Layers that form the ${\nu }_T$=1 Exciton Condensate
• Phase Transition in ν=2 Bilayer Quantum Hall State
• Onset of Interlayer Phase Coherence in a Bilayer Two-Dimensional Electron System: Effect of Layer Density Imbalance
• Spin Degree of Freedom in the nu =1 Bilayer Electron System Investigated via Nuclear Spin Relaxation
• Spin Transition in Strongly Correlated Bilayer Two Dimensional Electron Systems
• Dipolar Excitons, Spontaneous Phase Coherence, and Superfluid-Insulator Transition in Bi-layer Quantum Hall Systems at $\nu =1$
• Evidence for a finite temperature phase transition in a bilayer quantum Hall system
• Role of density imbalance in an interacting bilayer hole system
• Bias-voltage induced phase-transition in bilayer quantum Hall ferromagnets
• Coherent Tunneling in Exciton Condensates of Bilayer Quantum Hall Systems
• Hybridization of electron subbands in a double quantum well at quantizing magnetic field
• Evolution of the bilayer nu = 1 quantum Hall state under charge imbalance

Cited by in corpus (21)

• Excitonic superfluid phase in Double Bilayer Graphene
• Quantum Hall Drag of Exciton Superfluid in Graphene
• Trial Wavefunctions for ν= 1/2 + 1/2 Quantum Hall Bilayers
• Anomalous Exciton-Condensation in Graphene Bilayers
• Quantum Hall Superfluids in Topological Insulator Thin Films
• Fractional quantum Hall effects in bilayers in the presence of inter-layer tunneling and charge imbalance
• Quantitative description of Josephson-like tunneling in ${\nu }_T=1$ quantum Hall bilayers
• Interaction Driven Quantum Phase Transitions in Fractional Topological Insulators
• Critical Tunneling Currents in Quantum Hall Superfluids: Pseudospin-Transfer Torque Theory
• Precursors to Exciton Condensation in Quantum Hall Bilayers
• $s$-wave paired composite-fermion electron-hole trial state for quantum Hall bilayers with $\nu =1$
• Josephson vortex motion as a source for dissipation of superflow of e-h pairs in bilayers
• XY* transition and extraordinary boundary criticality from fractional exciton condensation in quantum Hall bilayer
• Interaction-induced Interlayer Charge Transfer in the Extreme Quantum Limit
• Evidence for a Superfluid-to-solid Transition of Bilayer Excitons
• Clausius-Clapeyron Relations For First Order Phase Transitions In Bilayer Quantum Hall Systems
• Bilayer quantum Hall system at ${\nu }_t=1$: pseudospin models and in-plane magnetic field
• Pairing of Composite-Electrons and Composite-Holes in ${\nu }_T=1$ Quantum Hall Bilayers
• Successive electron-vortex binding in quantum Hall bilayers at $\nu =\frac{1}{4}+\frac{3}{4}$
• Electron spin polarization by isospin ordering in correlated two-layer quantum Hall systems
• Density dependence of the excitation gaps in an undoped Si/SiGe double-quantum-well heterostructure