Hybridization of single- and double-layer behavior in a double-quantum-well structure

Davies, A. G.; Barnes, C. H. W.; Zolleis, K. R.; Nicholls, J.E.; Simmons, M. Y.; Ritchie, D. A.

doi:10.1103/physrevb.54.r17331

Cited by 50 publications

(52 citation statements)

References 19 publications

(17 reference statements)

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“…Such a phasecorrelated interaction might re-normalize the subband. Quite possibly, a hybridization might occur, qualitatively similar to what has been observed in coupled double quantum wells by Davies et al [30]. Admittedly, this is, at present, pure speculation, but at the very least it suggests a closer investigation into the ISBS puzzle.…”

Section: Inter-subband Scatteringsupporting

confidence: 65%

Quasiparticle dynamics in ballistic weak links under weak voltage bias: an elementary treatment

Kroemer

1999

Superlattices and Microstructures

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A simple one-dimensional model for SNS weak links in the ballistic limit is presented. In the presence of a bias voltage, the quasiparticle state at any given instant of time is described as a superposition of that particular set of phase-dependent Andreev bound states that belongs to the specific phase difference present at this instant between the superconducting banks. The treatmentÑbasically a form of adiabatic perturbation theoryÑhas a strong formal similarity to the treatment of the k-space dynamics of an electron in a periodic potential under perturbation by an external electric field, sufficiently strong to cause transitions across the energy gaps between bands (Zener tunneling). It is shown that the quasiparticle wave function retains its phase information during analogous transitions between Andreev bands. The experimental observation of Shapiro steps at one-half the canonical voltage follows naturally from the model, along with some of the experimental properties of these steps, especially their much weaker temperature dependence, compared to the canonical steps.

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Section: Inter-subband Scatteringsupporting

confidence: 65%

Quasiparticle dynamics in ballistic weak links under weak voltage bias: an elementary treatment

Kroemer

1999

Superlattices and Microstructures

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“…In this Letter we show that an externally applied electric field through a gate bias, which takes one away (off-balance) from the balanced condition and introduces [9] unequal layer electron densities is potentially an extremely powerful experimental tool in studying the ν=2 bilayer quantum phase transitions. Our results indicate that using an external gate bias as a tuning parameter, a technique already extensively used [6,10,11] in experimental studies of bilayer structures, should lead to direct experimental observations of the predicted quantum phases in ν=2 bilayer systems and the continuous transitions between them in both transport measurements [6,10,11] and in spin polarization measurements through NMR Knight shift experiments [12].…”

mentioning

confidence: 97%

Electromodulation of the Bilayeredν=2Quantum Hall Phase Diagram

1999

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We make a number of precise experimental predictions for observing the various magnetic phases and the quantum phase transitions between them in the ν=2 bilayer quantum Hall system. In particular, we analyze the effect of an external bias voltage on the quantum phase diagram, finding that a finite bias should readily enable the experimental observation of the recently predicted novel canted antiferromagnetic phase in transport and spin polarization measurements.PACS numbers: 73.40.Hm; 75.20.Kz Recent theoretical work [1][2][3] predicts the existence of a novel canted antiferromagnetic (C) phase in the ν=2 bilayer quantum Hall system under quite general experimental conditions, and encouraging experimental evidence in its support has recently emerged through inelastic light scattering spectroscopy [4,5] and transport measurements [6]. Very recent theoretical works have shown that such a C-phase may exist [7] in a multilayer superlattice system (with ν=1 per layer), and that in the presence of disorder-induced-interlayer tunneling fluctuations the C-phase may break up into a rather exotic spin Bose glass phase [8] with the quantum phase transition between the C-phase and the Bose glass phase being in the same universality class as the two-dimensional superconductor-insulator transition in the dirty boson system. In this Letter we consider the effect of an external electric field induced electromodulation (through an applied gate bias voltage) of the ν=2 bilayer quantum phase diagram. Our goal is to provide precise experimental predictions which will facilitate direct and unambiguous observations of the various magnetic phases, and more importantly the quantum phase transitions among them. We find the effect of a gate bias to be quite dramatic on the ν=2 bilayer quantum phase diagram. In particular, a finite gate bias makes the C-phase more stable which could now exist even in the absence of any interlayer tunneling in contrast to the situations considered in references [1][2][3] where the interlayer tunneling induced finite symmetric-antisymmetric gap was crucial in the stability of the C-phase. Thus, a finite gate bias, according to our theoretical calculations presented here, has a qualitative effect on the ν=2 bilayer quantum phase diagram -it produces a spontaneously interlayer-coherent canted antiferromagnetic phase which exists even in the absence of any inter-layer tunneling. The prediction of this spontaneously coherent canted (CC) phase is one of the new theoretical results of this paper. The theoretical construction of the bilayer ν=2 quantum phase diagram and predicting its experimental consequences in the presence of the bias voltage are our main results.The bilayer ν=2 system is characterized by five independent energy scales: the cyclotron energy, ω c (we takeh=1 throughout); the interlayer tunneling energy characterized by ∆ SAS , the symmetric-antisymmetric energy gap; the Zeeman energy or the spin-splitting ∆ z ; the intralayer Coulomb interaction energy and the interlayer Coulomb interaction e...

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“…Nevertheless, the data of Fig. 5 point strongly to an anticrossing behaviour, such as has been observed in GaAs/AlGaAs DQWs [5][6][7]. Comparing the measured data with the self-consistently calculated values [8] of the electron densities (plotted as lines in Fig.…”

Section: Methodsmentioning

confidence: 89%