### ?

## Аномальный сигнал антистоксового рассеяния как индикатор макрозаполненных магнитоэкситонных уровней в режиме КЭХ

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. It has been shown that this line can be attributed to the formation of an ensemble of long-lived collective excitations in the ferromagnetic phase at a filling factor of v = 2.

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

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., 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

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., Kaysin B. D., Volosheniuk S. et al., 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 ...

Added: October 31, 2019

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., 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., 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., 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

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

Горбунов А. В., Кулик Л. В., Kuznetsov V. et al., Письма в Журнал экспериментальной и теоретической физики 2017 Т. 106 № 10 С. 651-654

We demonstrate that non-equilibrium spin excitations drift to macroscopically large distances in a 2D electron gas (symmetrically doped GaAs/AlGaAs quantum well) in a quantizing magnetic field at filling factor $\nu $ = 2. The effect is induced by low-temperature photoexcitation of a dense ensemble of long-lived ($\sim 1 $ ms) spin excitations − cyclotron spin-flip magnetoexcitons. The spin excitation ...

Added: December 11, 2017

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

Kugel K., Kovaleva N. N., Kusmartseva O. E. et al., Journal of Physics: Conference Series 2017 Vol. 833 No. 1 P. 012005-1-012005-12

Materials, consisting of Jahn-Teller (JT) ions, such as cuprates and manganites, display many outstanding properties, including high temperature superconductivity and colossal magnetoresistance. There, the role of JT effect, although widely recognized, is still elusive. Here we show that these materials have vibronic excitations, related to local deformations rotating around JT ions in the dynamic limit, ...

Added: October 17, 2017

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

Pudalov V. M., Gershenson M. E., Kojima H., Physical Review B: Condensed Matter and Materials Physics 2014 Vol. 90 No. 7 P. 075147-1-075147-17

We have experimentally studied the renormalized effective mass m* and Dingle temperature TD in two spin subbands with essentially different electron populations. Firstly, we found that the product m*T_D that determines the damping of quantum oscillations, to the first approximation, is the same in the majority and minority subbands even at a spin polarization degree ...

Added: March 14, 2016

Миронов Б. Н., Асеев С. А., Sokolik A. A. et al., Журнал экспериментальной и теоретической физики 2018 Т. 154 № 3(9) С. 496-505

Исследована модификация графенового листа, полученного методом химического газофазного осаждения на медной мелкоячеистой сетке, под действием мощного фемтосекундного лазерного излучения. Установлено, что процесс длительного облучения образца в вакууме сопровождается 1) разрывом углеродных связей, о чем свидетельствует уменьшение яркости рефлексов, отвечающих дифракции электронного пучка на графене, и 2) образованием новых продуктов, о чем свидетельствуют появление новых дифракционных ...

Added: October 21, 2018

Kulik L. V., Kuznetsov V. A., Gorbunov A. V. et al., Scientific Reports 2018 Vol. 8 No. 1 P. 1-6

We report on optical visualization of spin propagation more than 100 µm. We present an electronic system in a new state of aggregation, the magnetofermionic condensate, in which the lowest-energy spin excitations − photoexcited spin-triplet magnetoexcitons – freely propagate over long distances, in the order of a millimeter, which implies non-diffusion spin transport. Our results open ...

Added: September 3, 2018

Kagan M., Mazur E. A., / Cornell University. Series "Working papers by Cornell University". 2020. No. arXiv:2006.13303.

The properties of a two-dimensional low density (n<<1) electron system with strong onsite Hubbard attraction U>W (W is the bandwidth) in the presence of a strong random potential V uniformly distributed in the range from -V to +V are considered. Electronic hoppings only at neighboring sites on the square lattice are taken into account, thus ...

Added: June 26, 2020

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

Ogorodnikov L.L., S.S. Vergeles, Optics Letters 2018 Vol. 43 No. 4 P. 651-654

We study the output emission statistics of a random continuous-wave Raman fiber laser. The signal evolution is governed by a generalized nonlinear Schrödinger equation (NLSE) with inserted gain. The statistics are close to the Rayleigh one, and the deviations are caused by the Kerr nonlinearity. To characterize the deviations, we analytically find the mean of ...

Added: February 8, 2018

V.M. Pudalov, Reznikov M., Kuntsevich A. et al., Journal of Low Temperature Physics 2015 Vol. 181 No. 3-4 P. 99-112

This paper describes recent developments in experimental techniques for thermodynamic measurements. Particularly, we focus on the derivatives of the chemical potential with respect to magnetic field and temperature. The former enables to determine the spin magnetization per electron and the latter the entropy per electron. We briefly describe recent results obtained with these techniques and ...

Added: March 14, 2016

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

Budkov Y., Kolesnikov A. L., Polymer Science - Series C 2018 Vol. 60 No. Supplement 1 P. 148-159

Theoretical models of the conformational behavior of flexible polymer chains in mixed solvents enunciated in the world literature during the last decade are critically reviewed. Models describing different mechanisms of coil-to-globule transitions in a good solvent induced by cosolvent addition are highlighted. Special attention is given to the analysis of theoretical approaches to describing the ...

Added: November 30, 2018