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Possible Magnetic Background of the Metal-Insulator Transition in Two-Dimensional Correlated Electron System
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Whether the apparent metal-insulator transition in two-dimensional (2D) correlated electron system is a true quantum phase transition or is a crossover phenomena—this question is in the core of ongoing debates. I present here a novel scenario of this phenomenon, based on experimental finding of the two-phase state in the correlated 2D system. The transport features in the suggested picture are the finite temperature phenomena and a consequence of the magnetic phase transition; the latter manifests in the sign change of the spin magnetization-per-electron. Physically, the magnetic transition means changing the tendency of the two-phase system to either paramagnetic Fermi liquid state (high density), or to the disordered ferromagnet (low density).
Lunkin A., Tikhonov K., Feigelman M., Journal of Physics and Chemistry of Solids 2017 P. 1–8
We developed a general approach to the calculation of power-law infrared asymptotics of spin-spin correlation functions in the Kitaev honeycomb model with different types of perturbations. We have shown that in order to find these correlation functions, one can perform averaging of some bilinear forms composed out of free Majorana fermions, and we presented the ...
Added: February 18, 2019
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
Lunkin A., Tikhonov K., Feigelman M., JETP Letters 2016 Vol. 103 No. 2 P. 117–121
We consider the spin-1/2 model on the honeycomb lattice [A. Kitaev, Ann. Phys.321, 2 (2006)] in the presence of a weak magnetic field h≪J. Such a perturbation treated in the lowest nonvanishing order over h leads [K.S. Tikhonov, M.V. Feigel’man, and A.Yu. Kitaev, Phys. Rev. Lett.106, 067203 (2011)] to a power-law decay of irreducible spin ...
Added: November 22, 2018
V.M. Pudalov, Kuntsevich A., Gershenson M. E. et al., Physical Review B: Condensed Matter and Materials Physics 2018 Vol. 98 No. 155109 P. 1–15
We report temperature and density dependences of the spin susceptibility of strongly interacting electrons in Si inversion layers. We measured (i) the itinerant electron susceptibility χ∗ from the Shubnikov-de Haas oscillations in crossed magnetic fields and (ii) thermodynamic susceptibility χTsensitive to all the electrons in the layer. Both χ∗ and χT are strongly enhanced with lowering the electron density in the metallic ...
Added: October 26, 2018
Belykh V. V., Kuntsevich A., Glazov M. M. et al., Physical Review X 2018 Vol. 8 P. 031021-1–031021-8
Manifestations of quantum interference effects in macroscopic objects are rare. Weak localization is one
of the few examples of such effects showing up in the electron transport through solid state. Here, we show
that weak localization becomes prominent also in optical spectroscopy via detection of the electron spin
dynamics. In particular, we find that weak localization controls the ...
Added: September 10, 2018
Pudalov V.M., Morgun L., Kuntsevich A.Yu, Journal of Superconductivity and Novel Magnetism 2017 Vol. 30 No. 3 P. 783–787
Strongly interacting two-dimensional (2D) carrier system has a tendency to spontaneous spin magnetization and mass divergence. Numerous experiments aimed to reveal these instabilities were not entirely convincing. In particular, spin susceptibility of itinerant electrons, determined from quantum oscillations, remains finite at the critical density of the 2D metal-insulator transition (MIT), n = n (c) . ...
Added: October 16, 2017
S.V.Demishev, V.V.Glushkov, Lobanova I. I. et al., Scientific Reports 2016 Vol. 6 P. 22101-1–22101-7
Intrinsic phase coherence between individual topologically stable knots in spin arrangement –
skyrmions – is known to induce the crystalline-like structure in the A-phase of non-centrosymmetric
MnSi with chiral spin-orbit interaction. Here we report the experimental evidence for two types of
the skyrmion lattice (SL) inside the A-phase of MnSi, which are distinguished by different coupling to
the anisotropic ...
Added: February 16, 2017
Teneh N., Kuntsevich A., Pudalov V. et al., Physical Review Letters 2012 Vol. 109 P. 226403
We report thermodynamic magnetization measurements of two-dimensional electrons in several highmobility
Si metal-oxide-semiconductor field-effect transistors. We provide evidence for an easily polarizable
electron state in a wide density range from insulating to deep into the metallic phase. The
temperature and magnetic field dependence of the magnetization is consistent with the formation of
large-spin droplets in the insulating phase. These ...
Added: October 15, 2016
Burovskiy E., Szyniszewski, M., Journal of Physics: Conference Series 2015 Vol. 592 P. 012057
We develop a systematic strong coupling approach for studying an extended t-V model with interactions of a finite range. Our technique is not based on the Bethe ansatz and is applicable to both integrable and non-integrable models. We illustrate our technique by presenting analytic results for the ground state energy (up to order 7 in t/V), the current ...
Added: September 8, 2016
Burovskiy E., Kozik E., Troyer M. et al., Physical Review B: Condensed Matter and Materials Physics 2013 Vol. 87 P. 205102
We study the thermodynamics of the three-dimensional Hubbard model at half filling on approach to the Néel transition by means of large-scale unbiased diagrammatic determinant Monte Carlo simulations. We obtain the transition temperature in the strongly correlated regime, as well as the temperature dependence of the energy, entropy, double occupancy, and nearest-neighbor spin correlation function. ...
Added: September 7, 2016
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
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
Kuntsevich A., Tupikov Y. V., Pudalov V. M. et al., Nature Communications 2015 Vol. 6 P. 7298-1–7298-6
Charged plasma and Fermi liquid are two distinct states of electronic matter intrinsic to dilute
two-dimensional electron systems at elevated and low temperatures, respectively. Probing
their thermodynamics represents challenge because of lack of an adequate technique. Here,
we report a thermodynamic method to measure the entropy per electron in gated structures. Our technique appears to be three orders ...
Added: March 14, 2016