scholarly journals Thermodynamics of free and bound magnons in graphene

2021 ◽  
Author(s):  
Andrew T. Pierce ◽  
Yonglong Xie ◽  
Seung Hwan Lee ◽  
Patrick R. Forrester ◽  
Di S. Wei ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Chemical Potential ◽  
Quantum Hall ◽  
Ferromagnetic Phase ◽  
Monolayer Graphene ◽  
Long Distance ◽  
Rotation Symmetry ◽  
Quantum Hall Regime ◽  
Hall Regime ◽  
Local Measurements

AbstractSymmetry-broken electronic phases support neutral collective excitations. For example, monolayer graphene in the quantum Hall regime hosts a nearly ideal ferromagnetic phase at specific filling factors that spontaneously breaks the spin-rotation symmetry1–3. This ferromagnet has been shown to support spin-wave excitations known as magnons that can be electrically generated and detected4,5. Although long-distance magnon propagation has been demonstrated via transport measurements, important thermodynamic properties of such magnon populations—including the magnon chemical potential and density—have not been measured. Here we present local measurements of electron compressibility under the influence of magnons, which reveal a reduction in the gap associated with the ν = 1 quantum Hall state by up to 20%. Combining these measurements with the estimates of temperature, our analysis reveals that the injected magnons bind to electrons and holes to form skyrmions, and it enables the extraction of free magnon density, magnon chemical potential and average skyrmion spin. Our methods provide a means of probing the thermodynamic properties of charge-neutral excitations that are applicable to other symmetry-broken electronic phases.

scholarly journals GRAPHENE IN THE QUANTUM HALL REGIME: EFFECTS OF VACANCIES, SUBLATTICE POLARIZATION AND DISORDER

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2618-2627 ◽  
Author(s):  
ANA L. C. PEREIRA ◽  
PETER A. SCHULZ
Keyword(s):  
Quantum Hall ◽  
Tight Binding ◽  
Wave Functions ◽  
Hall Resistance ◽  
Monolayer Graphene ◽  
Binding Model ◽  
Quantum Hall Regime ◽  
Hall Regime ◽  
Valley Polarization ◽  
Disorder Effect

We investigate the effects of vacancies, disorder and sublattice polarization on the electronic properties of a monolayer graphene in the quantum Hall regime. Energy spectra as a function of magnetic field and the localization properties of the states within the graphene Landau levels (LLs) are calculated through a tight-binding model. We first discuss our results considering vacancies in the lattice, where we show that vacancies introduce extra levels (or well-defined bands) between consecutive LLs. An striking consequence here is that extra Hall resistance plateaus are expected to emerge when an organized vacancy superlattice is considered. Secondly, we discuss the anomalous localization properties we have found for the lowest LL, where an increasing disorder is shown to enhance the wave functions delocalization (instead of inducing localization). This unexpected effect is shown to be directly related to the way disorder increasingly destroys the sublattice (valley) polarization of the states in the lowest LL. The reason why this anomalous disorder effect occurs only for the zero-energy LL is that, in absence of disorder, only for this level all the states are sublattice polarized, i.e., their wave functions have amplitudes in only one of the sublattices.

ANOMALOUS QUANTUM HALL RESISTANCE IN Al0.6Ga0.4As0.1Sb0.9/InAs QUANTUM WELL WITH TUNABLE CARRIER DENSITY

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1419-1423
Author(s):  
K. OTO ◽  
S. TAMIYA ◽  
S. ISHIDA ◽  
A. OKAMOTO ◽  
I. SHIBASAKI
Keyword(s):  
Quantum Well ◽  
Carrier Transport ◽  
Chemical Potential ◽  
Lattice Mismatch ◽  
Quantum Hall ◽  
Hall Resistance ◽  
Persistent Photoconductivity ◽  
Quantum Hall Regime ◽  
Hall Regime ◽  
Magneto Resistance

We have investigated magneto-resistance in InAs/Al 0.6 Ga 0.4 As 0.1 Sb 0.9 quantum well (QW), where the lattice mismatch at the interface is less than 2 %. The carrier concentration can be tuned by using positive and negative persistent photoconductivity effect, selected by the wavelength (λ=1.6μ m or 0.95 μm) of illumination. The electrons and holes coexist in the QW structure, and the contribution of both carriers should be taken into account. The observed deviation of Hall plateaus from the quantized value can be understood by considering the carrier transport in both electron and hole edge channels, and the equilibrium of chemical potential at the all electrodes in the sample. The transport properties in quantum Hall regime measured in the samples with the QW thickness of 15, 50 and 150 nm are reported.

scholarly journals Magnetotransport of Monolayer Graphene with Inert Gas Adsorption in the Quantum Hall Regime

2018 ◽  
Vol 969 ◽  
pp. 012130 ◽  
Author(s):  
A Fukuda ◽  
D Terasawa ◽  
A Fujimoto ◽  
Y Kanai ◽  
K Matsumoto
Keyword(s):  
Gas Adsorption ◽  
Quantum Hall ◽  
Inert Gas ◽  
Monolayer Graphene ◽  
Quantum Hall Regime ◽  
Hall Regime

scholarly journals Nonlinear optics in the fractional quantum Hall regime

Nature ◽  
2019 ◽  
Vol 572 (7767) ◽  
pp. 91-94 ◽  
Author(s):  
Patrick Knüppel ◽  
Sylvain Ravets ◽  
Martin Kroner ◽  
Stefan Fält ◽  
Werner Wegscheider ◽  
...  
Keyword(s):  
Nonlinear Optics ◽  
Quantum Hall ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Quantum Hall Regime ◽  
Hall Regime

Current distribution in antidot arrays close to the quantum Hall regime

1999 ◽  
Vol 60 (4) ◽  
pp. 2561-2570 ◽  
Author(s):  
Rolf R. Gerhardts ◽  
Johannes Groß
Keyword(s):  
Current Distribution ◽  
Quantum Hall ◽  
Quantum Hall Regime ◽  
Hall Regime ◽  
Antidot Arrays

MACH-ZEHNDER INTERFEROMETER IN THE INTEGER QUANTUM HALL REGIME: A QUANTUM DISSIPATIVE MODEL

2009 ◽  
Vol 23 (12n13) ◽  
pp. 2927-2932
Author(s):  
E. A. ASANO
Keyword(s):  
Quantum Hall ◽  
Zehnder Interferometer ◽  
The Novel ◽  
Quantum Dissipation ◽  
Quantum Hall Regime ◽  
Hall Regime ◽  
Frequency Independent ◽  
Integer Quantum ◽  
Dissipative Model ◽  
Mach Zehnder Interferometer

We study properties of the simplest type of electron interferometer, the Mach-Zehnder Interferometer (MZI) in the Integer Quantum Hall (IQH) regime. In this work, in order to analyse the novel experimental results reported by I. Neder et al. [Phys. Rev. Lett.96, 016804 (2006)] which makes questionable the validity of Landauer-Buttiker formalism in the IQH regime, we have derived expressions for tunneling currents through the electronic MZI system whithin the model of quantum dissipation induced by an environment. In this model the MZI system is coupled to a dissipative environment, where the dissipation is introduced by coupling the MZI system to a frequency-independent Ohmic impedance Z(ω) = R.

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