Antilevitation of Landau levels in vanishing magnetic fields

Pan, W.; Baldwin, K. W.; West, K. W.; Pfeiffer, L. N.; Tsui, D. C.

doi:10.1103/physrevb.94.161303

Cited by 5 publications

(2 citation statements)

References 27 publications

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“…where ω c =eB/m is the cyclotron frequency, τ is the mean free scattering time, and ò(n)=(n+1/2)ÿω c are the high-field Landau level energies for conventional 2DEGs. This theory, which has continued to be subject to debate in conventional 2DEGs [29][30][31] and has just begun to be studied in graphene [32], yields a cross-over into the quantum Hall regime at ω c τ=1, corresponding semiclassically to the region where the scattering length becomes comparable to the magnetic length and phase-coherent Landau level orbits can be established. It is notable that the ω c τ=1 condition is equivalent to a B=1/μ condition, which for our samples is just under 2 T, the point at which the half-filling conductance asymmetries are at a maximum (figures 4(a) and (b)).…”

Section: Discussionmentioning

confidence: 98%

Formation of the n = 0 Landau level in hybrid graphene

et al. 2018

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The minimum of 4-terminal conductance occurring as carrier density is tuned through its charge neutral point has proven to be a robust empirical feature of graphene, persisting with changes to temperature, applied magnetic field, substrate, and layer thickness, though the theoretical mechanisms involved in transport about this point-vanishing density of states, conventional band gap opening, and broken-symmetry quantum Hall mobility gaps-vary widely depending on the regime. In this paper, we report on observations of a regime where the 4-terminal conductance minimum ceases to exist: transport in monolayer graphene connected to bilayer graphene during the onset of the quantum Hall effect. This observed increase in conductance is accompanied by decreases in conductance at the half-filling of the Landau levels adjacent to the charge-symmetric, zero-energy level. As monolayer and bilayer graphene have distinct zero-energy levels that form about the charge neutral point, our observations suggest that competitions between the differing many-body orderings of these states as they emerge may underlie these anomalous conductances.

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Section: Discussionmentioning

confidence: 98%

Formation of the n = 0 Landau level in hybrid graphene

et al. 2018

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“…This is analogous to the use of semitransparent gates in optical experiments. Our motivation for this is experimentation in heterojunction insulated gate field effect transistors (HIGFETS) [9][10][11][12][13] which are semiconductor devices known to give particularly low disorder and wide density tunability. However, for the proof-of-concept demonstration in this paper we present data on a Si metal-oxide-semiconductor field-effect transistor (MOSFET), a well-understood device whose large disorder is expected to render its conductivity nearly independent of frequency in our measuring range.…”

Section: Introductionmentioning

confidence: 99%

Resistively loaded coplanar waveguide for microwave measurements of induced carriers

Freeman¹,

Lu²,

Engel³

2022

Preprint

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We describe the use of a coplanar waveguide whose slots are filled with resistive film, a resistively loaded coplanar waveguide (RLCPW), to measure two dimensional electron systems (2DES). The RLCPW applied to the sample hosting the 2DES provides a uniform metallic surface serving as a gate, to control the areal charge density of the 2DES.As a demonstration of this technique we present measurements on a Si MOSFET, and a model that successfully converts microwave transmission coefficients into conductivity of a nearby 2DES capacitively coupled to the RLCPW. We also describe the process of fabricating the highly resistive metal film required for fabrication of the RLCPW.

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Localization and interference induced quantum effects at low magnetic fields in InGaAs/GaAs structures

Savelyev

Arapov

Gudina

et al. 2021

Low Temperature Physics

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The longitudinal ρxx(B, T) and Hall ρxy(B, T) resistances are experimentally investigated in n-InGaAs/GaAs nanostructures with a single and double quantum wells in the magnetic field range B = 0–2.5 T and temperatures T = 1.8–20 K. It is shown that the origin of the temperature-independent point located at ωcτ≅1 on the ρxx(B, T) curves is due to the combined action of the classical cyclotron motion and the quantum interference effects of weak localization and electron-electron interaction. The results obtained indicate that the transition from the dielectric phase to the phase of the quantum Hall effect is a crossover from weak localization (quantum interference effects in a weak magnetic field) to strong localization in quantizing magnetic fields in the quantum Hall effect regime.

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Antilevitation of Landau levels in vanishing magnetic fields

Cited by 5 publications

References 27 publications

Formation of the n = 0 Landau level in hybrid graphene

Formation of the n = 0 Landau level in hybrid graphene

Resistively loaded coplanar waveguide for microwave measurements of induced carriers

Localization and interference induced quantum effects at low magnetic fields in InGaAs/GaAs structures

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