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Exchange energy renormalization in quantum Hall ferromagnets with strong Coulomb interaction
Physical Review B: Condensed Matter and Materials Physics. 2019. Vol. 100. No. 4. P. 041407-1-041407-5.
An unusual behavior of the exchange energy scale of a quantum Hall ferromagnet with ν=1 was found in strongly correlated two-dimensional electron systems based on MgZnO/ZnO heterostructures. The exchange contribution, entering the energy of a collective excitation, was probed by means of inelastic light scattering. It was established that, in a wide range of electron densities corresponding to the Wigner-Seitz parameter 7<rs<11, this contribution is on the order of the cyclotron energy, which is notably different from the typical scale of e2/ɛℓB that is typical for weakly interacting systems. The same trend was confirmed via numerical calculations.
A.B. Van'kov, Kukushkin I., Physical Review B: Condensed Matter and Materials Physics 2020 Vol. 102 No. 23 P. 235424-1-235424-6
Anomalous behavior of spin stiffness is revealed in ZnO-based two-dimensional electron systems (2DESs)
with strong Coulomb interaction and Wigner-Seitz parameter r_s > 6. The spin stiffness is extracted directly from
the quadratic k-dispersion of spin excitons at ν = 1 probed by inelastic light scattering. The resulting values are
found to be dramatically rescaled compared to the case ...
Added: January 22, 2021
A. B. Van'kov, Koreyev A. S., P. S. Berezhnoy et al., Physical Review B: Condensed Matter and Materials Physics 2022 Vol. 106 No. 24 Article 245308
In strongly correlated quantum Hall ferromagnets with noninteger filling factors between ν = 1 and ν =
3/2, evidence of offbeat spin textures is obtained. The platforms for the study are two-dimensional electron
systems based on MgZnO/ZnO heterostructures, in which the parameters of Zeeman and exchange energies are
inconsistent with ordinary skyrmions. Experimental probing of magnetic order is ...
Added: December 29, 2022
Vankov A., Kukushkin I., Physical Review B: Condensed Matter and Materials Physics 2021 Vol. 104 Article 165144
In ZnO-based two-dimensional electron systems with strong Coulomb interaction, the anomalous spin-exciton
branch is revealed. As probed by inelastic light scattering, in a ferromagnetic quantum-Hall state with the filling
factor ν = 2, a spin exciton has a negative momentum dispersion with steepness dependent on the electron
density. The negative dispersion of the spin exciton is associated with ...
Added: December 20, 2021
Vankov A., Кайсин Б. Д., Kukushkin I., Письма в Журнал экспериментальной и теоретической физики 2018 Т. 107 № 2 С. 110-114
In the two-dimensional electron systems with strong coupling in MgZnO/ZnO heterostructures, the thermal
behavior of Ising quantum Hall ferromagnets at the filling factor nu=2 has been studied. The spin polarization
of Hall ferromagnets has been detected by measuring the signal related to the inelastic light scattering by
intrasubband spin excitons. A stepwise change in the spin polarization at ...
Added: September 11, 2018
Vankov A., Solovyev V., Kaysin B. et al., Physical Review B: Condensed Matter and Materials Physics 2016 Vol. 94 P. 1552041-1552046
The neutral excitations in two-dimensional electron systems (2DES) confined at MgZnO/ZnO heterojunc- tions were studied by a resonant inelastic light scattering (ILS) technique. At zero magnetic field the ILS spectra of intra- and intersubband collective excitations are detected in the wavelength range close to the ZnO direct band gap. The intersubband spectrum is represented by ...
Added: October 21, 2016
Vankov A., Kukushkin I., Письма в Журнал экспериментальной и теоретической физики 2020 Т. 112 № 1 С. 62-67
The Raman study of strongly interacting two-dimensional electron systems based on ZnO/MgZnO has revealed an anomalously intense spectral line of the anti-Stokes component of the spin exciton. This line is manifested near the filling factor v = 2 at the ferromagnetic ordering of the spin subsystem, whereas it is not observed at the paramagnetic ordering. ...
Added: January 25, 2021
Vankov A., Kukushkin I., JETP Letters 2017 Vol. 105 No. 6 P. 380-383
The magnetic field dynamics of intersubband collective excitations in two-dimensional electron systems based on Mg_xZn_{1−x}O/ZnO heterostructures is studied by the Raman scattering method. It is found that, upon the change in the spin polarization under conditions of the transition from the filling factor ν=2 to ν=1, the energy of the intersubband magnetoplasmon changes considerably. The ...
Added: November 30, 2017
Vankov A., Kaysin B. D., Kukushkin I., JETP Letters 2019 Vol. 110 No. 4 P. 296-300
The behavior of the degree of spin polarization and the specific exchange energy near the Hall ferromagnetic state with filling factor ν = 1 in strongly interacting two-dimensional electron systems in MgZnO/ZnO heterostructures is investigated. These characteristics have been determined by measuring the spectra of inelastic light scattering by the collective excitations of the electron ...
Added: October 31, 2019
Vankov A., Kukushkin I., Кулик Л. В. et al., JETP Letters 2017 Vol. 105 No. 6 P. 380-383
The magnetic field dynamics of intersubband collective excitations in two-dimensional electron systems
based on Mg Zn O/ZnO heterostructures is studied by the Raman scattering method. It is found that,
upon the change in the spin polarization under conditions of the transition from the filling factor to
, the energy of the intersubband magnetoplasmon changes considerably. The performed theoretical
analysis ...
Added: June 13, 2017
Vankov A., Бисти В. Е., Кулик Л. В. et al., Physics-Uspekhi 2015 Vol. 4 No. 58 P. 315-329
Experimental and theoretical research on neutral
excitations in a two-dimensional electron gas in a strong mag netic field is reviewed. Methods for calculating excitation en ergies in the strong-field limit for integer and noninteger filling
factors are considered. The effects of impurities and of the
nonideality of the two-dimensional system on the excitation
spectrum are examined. Experimental results that have been
obtained ...
Added: March 6, 2017
Vankov A., Kaysin B. D., Kukushkin I., Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 98 P. 121412-121412
We investigate the impact of Coulomb correlations on the low-energy collective excitations in two-dimensional electron systems in the quantum Hall state ν = 2. The collective excitations are studied using inelastic light scattering in the set of MgZnO/ZnO heterostructures with high-mobility two-dimensional electrons. The study focuses on the lowest-energy collective excitations in the paramagnetic state ...
Added: November 25, 2018
Nagy B., Khaydukov Y. N., Kiss L. F. et al., Journal of Superconductivity and Novel Magnetism 2013 Vol. 26 P. 1957-1961
Thickness (dF) and concentration (x) dependence of the Curie temperature of NixCu100-x(dF) ferromagnetic alloy layers (x =0.55,0.65, dF =[3nm{\div}12nm]) being in contact with a vanadium layer was studied. The Curie temperature of the ferromagnetic layers depends on the thickness when it is comparable with the interface layer between the F and the vanadium layers, which ...
Added: September 28, 2015
Kuznetsov V. A., Kulik L. V., Velikanov M. D. et al., Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 98 No. 20 P. 205303-1-205303-9
Three-particle complexes consisting of two holes in the completely filled zero-electron Landau level and an excited electron in the unoccupied first Landau level are investigated in a quantum Hall insulator. The distinctive features of these three-particle complexes are an electron-hole mass symmetry and the small energy gap of the quantum Hall insulator itself. Theoretical calculations ...
Added: November 20, 2018
Kulik L., Zhuravlev A. S., Musina L. I. et al., Nature Communications 2021 Vol. 12 Article 6477
Two-dimensional electron systems in a quantizing magnetic field are regarded as of
exceptional interest, considering the possible role of anyons—quasiparticles with non-boson
and non-fermion statistics—in applied physics. To this day, essentially none but the fractional
states of the quantum Hall effect (FQHE) have been experimentally realized as a system with
anyonic statistics. In determining the thermodynamic properties of anyon ...
Added: December 20, 2021
Dziom V., Shuvaev A. V., Shchepetilnikov A. et al., Physical Review B: Condensed Matter and Materials Physics 2019 Vol. 99 No. 4 Article 045305
The integer quantum Hall effect is a well-studied phenomenon at frequencies below about 100 Hz. The plateaus in high-frequency Hall conductivity were experimentally proven to retain up to 33 GHz, but the behavior at higher frequencies has remained largely unexplored. Using continuous-wave terahertz spectroscopy, the complex Hall conductivity of GaAs/AlGaAs heterojunctions was studied in the ...
Added: December 11, 2020
Glushkov V. V., Demishev S. V., Samarin A. et al., Physica Status Solidi (B): Basic Research 2017 Vol. 254 No. 4 P. 1600571-1-1600571-5
Added: October 19, 2017
Ozaeta A., Vasenko A.S., Hekking F. W. et al., Physical Review B: Condensed Matter and Materials Physics 2012 Vol. 86 P. 060509-1-060509-5
We investigate the subgap transport properties of a S-F-Ne structure. Here S (Ne) is a superconducting (normal) electrode, and F is either a ferromagnet or a normal wire in the presence of an exchange or a spin- splitting Zeeman field respectively. By solving the quasiclassical equations we first analyze the behavior of the subgap current, ...
Added: September 28, 2015
Khomskii D. I., K.I. Kugel, Sboychakov A. O. et al., Journal of Experimental and Theoretical Physics 2016 Vol. 122 No. 3 P. 484-498
We analyze the role of local geometry in the spin and orbital interaction in transition metal compounds with orbital degeneracy. We stress that the tendency observed in the most studied case (transition metals in O6 octahedra with one common oxygen—common corner of neighboring octahedra—and with ~180° metal–oxygen–metal bonds), that ferro-orbital ordering renders antiferro-spin coupling and, ...
Added: February 18, 2017
Vasenko A.S., Kawabata S., Ozaeta A. et al., Journal of Magnetism and Magnetic Materials 2015 Vol. 383 P. 175-179
Ferromagnetic materials with exchange fields E_ex smaller or of the order of the superconducting gap Delta are important for applications of corresponding (s-wave) superconductor/ ferromagnet/ superconductor (SFS) junctions. Presently such materials are not known but there are several proposals how to create them. Small exchange fields are in principle difficult to detect. Based on our ...
Added: September 28, 2015
Kuznetsov V., Кулик Л. В., Журавлёв А. С. et al., Письма в Журнал экспериментальной и теоретической физики 2018 Т. 107 № 2 С. 104-107
В спектре фотолюминесценции двумерного электронного газа в квантующем магнитном поле, при факторе заполнения электронов ν=2, в условиях фотовозбуждения неравновесного ансамбля циклотронных магнитоэкситонов, обнаружены новые линии. Их энергия лежит в области, запрещенной для одночастичных оптических переходов: в диапазоне переходов из возбужденных состояний трехчастичных трансляционно-инвариантных комплексов - магнитотрионов. Предполагается, что новые линии связаны со сложным спектром внутреннего движения ...
Added: January 22, 2018
Kukushkin I., Vankov A., Kaysin B., Physical Review B: Condensed Matter and Materials Physics 2017 Vol. 96 P. 235401-1-235401-8
We perform a magneto-optical study of a two-dimensional electron systems in the regime of the Stoner
ferromagnetic instability for even quantum Hall filling factors on MgxZn1−xO/ZnO heterostructures. Under
conditions of Landau-level crossing, caused by enhanced spin susceptibility in combination with the tilting of the
magnetic field, the transition between two rivaling phases, paramagnetic and ferromagnetic, is traced in ...
Added: December 19, 2017
Gorbunov A., Vladimir A. Kuznetsov, Zhuravlev A. et al., Annalen der Physik 2019 P. 1800443-1800458
Experimental results on the properties of a recently discovered new collective state, the magnetofermionic condensate, are summarized herein. Condensation occurs in a fermionic system, a quantum Hall insulator (filling factor ν = 2), as a result of the formation of a dense ensemble of long-lived spin cyclotron magnetoexcitons, composite bosons. At temperatures below 1 K, ...
Added: May 29, 2019
Khrapai V., Physical Review B: Condensed Matter and Materials Physics 2023 Vol. 107 No. 24 Article L241401
A quantum Hall interferometer containing a grounded superconducting terminal is proposed. This geometry
allows to control the Andreev and normal scattering amplitudes of subgap Bogoliubov quasiparticles with the
Aharonov-Bohm phase, as well as with the constrictions defining the interferometer loop. The conductance
matrix of such a three-terminal NSN interference device exhibits a much richer behavior as compared to ...
Added: June 13, 2023
Antipov A., Seleznev V., Vakhtomin Y. et al., IOP Conference Series: Materials Science and Engineering (MSE) 2020 Vol. 781 No. 1 P. 012011-1-012011-5
Spectral characteristics of WSi and NbN superconducting single-photon detectors with different surface resistance and width of nanowire strips have been investigated in the wavelength range of 1.3-2.5 µm. WSi structures with narrower strips demonstrated better performance for detection of single photons in longer wavelength range. The difference in normalized photon count rate for such structures ...
Added: December 10, 2020