# Denis GolosovBar Ilan University | BIU · Department of Physics

Denis Golosov

PhD

## About

37

Publications

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676

Citations

## Publications

Publications (37)

We propose a single-site mean-field description, an analog of Weiss mean-field theory, suitable for narrow-band systems with correlation-induced hybridization at finite temperatures. Presently, this approach, based on the notion of a fluctuating onsite density matrix (OSDM), is developed for the case of extended Falicov-Kimball model (EFKM). In an...

We propose a single-site mean-field description, an analogue of Weiss mean-field theory, suitable for narrow-band systems with correlation-induced hybridisation at finite temperatures. Presently this approach, based on the notion of a fluctuating on-site density matrix (OSDM), is developed for the case of extended Falicov-Kimball model (EFKM). In a...

In an extended Falicov-Kimball model, an excitonic insulator phase can be stabilised at zero temperature. With increasing temperature, the excitonic order parameter (interaction-induced hybridisation on-site, characterised by the absolute value and phase) eventually becomes disordered, which involves fluctuations of both its phase and (at higher T)...

We consider quasi-two-dimensional gas of electrons in a typical Si-MOSFET, assuming repulsive contact interaction between electrons. Magnetisation and susceptibility are evaluated within the mean-field approach. Finite thickness of the inversion layer results in an interaction-induced electron wave function change, not found in both purely two-dime...

Motivated by recent experimental work on magnetic properties of Si-MOSFETs,
we report a calculation of magnetisation and susceptibility of electrons in an
inversion layer, taking into account the co-ordinate dependence of electron
wave function in the direction perpendicular to the plane. It is assumed that
the inversion-layer carriers interact via...

We have performed conductivity measurements on a Si-MOSFET sample with a slot
in the upper gate, allowing for different electron densities n_1 and n_2 across
the slot. Dynamic longitudinal resistance was measured by a standard lock-in
technique, while maintaining a large DC current through the source-drain
channel. We find that in a parallel magnet...

We consider a spinless extended Falicov--Kimball model at half-filling, for
the case of opposite-parity bands. Within the Hartree--Fock approach, we
calculate the excitation energies in the chiral phase, which is a possible
mean-field solution in the presence of a hybridisation. It is shown that the
chiral phase is unstable. We then briefly review...

DOI:https://doi.org/10.1103/PhysRevB.86.159905

Longitudinal resistivity in strong parallel magnetic fields up to B = 14 Tesla was measured in Si-MOSFET with a narrow slot (90nm) in the upper metallic gate that allows to apply different gate voltage across the slot and, therefore, to control the electron density n1 and n2 in two parts of the sample independently. The experimental scheme allows u...

We consider the excitonic insulator state (often associated with electronic
ferroelectricity), which arises on the phase diagram of an extended spinless
Falicov--Kimball model (FKM) at half-filling. Within the Hartree--Fock
approach, we calculate the spectrum of low-energy collective excitations in
this state up to second order in the narrow-band h...

Positive magnetoresistance (PMR) of a silicon MOSFET in parallel magnetic
fields B has been measured at high electron densities n >> n_c where n_c is the
critical density of the metal-insulator transition (MIT). It turns out that the
normalized PMR curves, R(B)/R(0), merge together when the field is scaled
according to B/B_c(n) where B_c is the fie...

A new minimal model is constructed for the doped manganese oxides which exhibit colossal magnetoresistance (CMR), involving broad spin-majority conduction band as well as nearly localised spin-minority electron states. A simple mean field analysis yields a temperature-dependent hybridised band structure with suppressed carrier weight at the Fermi l...

We report measurements on a Si-MOSFET sample with a slot in the upper gate, allowing for different electron densities n1,2 across the slot. The dynamic longitudinal resistance was measured by the standard lock-in technique, while maintaining a large DC current through the source-drain channel. We find that the conductance of the sample in a strong...

We report measurements on a Si‐MOSFET sample with a slot in the upper gate, allowing for different electron densities n1,2 across the slot. The dynamic longitudinal resistance was measured by the standard lock‐in technique, while maintaining a large DC current through the source‐drain channel. We find that the conductance of the sample in a strong...

We consider a model with competing double-exchange (ferromagnetic) and super-exchange (anti-ferromagnetic) interactions in the regime where phase separation takes places. The presence of a long range Coulomb interaction frustrates a macroscopic phase separation, and favors microscopically inhomogeneous configurations. We use the variational Hartree...

We report a series of magnetic and transport measurements on high-quality single crystal samples of colossal magnetoresistive manganites, La_{0.7} Ca_{0.3} Mn O_3 and Pr_{0.7} Sr_{0.3} Mn O_3. 1 % Fe doping allows Moessbauer spectroscopy study, which shows (i) unusual line broadening within the ferromagnetic phase and (ii) a coexistence of ferro- a...

We report a series of magnetic and transport measurments on high-quality single crystal manganate samples in the colossal magnetoresistive (CMR) regime. A small iron doping allows also for a Mössbauer spectroscopy study, showing both an unusual line broadening within the ferromagnetic phase and a coexistence of ferro- and paramagnetic contributions...

Lapses of transmission phase in transport through quantum dots are ubiquitous already in the absence of interaction, in which case their precise location is determined by the signs and magnitudes of the tunnelling matrix elements. However, actual measurements for a quantum dot embedded in an Aharonov-Bohm interferometer show systematic sequences of...

Measurements of the transmission phase in transport through a quantum dot embedded in an Aharonov-Bohm interferometer show systematic sequences of phase lapses separated by Coulomb peaks. Using a two-level quantum dot as an example we show that this phenomenon can be accounted for by the combined effect of asymmetric dot-lead coupling and interacti...

We calculate the energy of a boundary between ferro- and antiferromagnetic regions in a phase separated double-exchange magnet in two and three dimensions. The orientation dependence of this energy can significantly affect the geometry of the phase-separated state in two dimensions, changing the droplet shape and possibly stabilizing a striped arra...

We investigate the zero-temperature phase diagram and spin-wave properties of a double exchange magnet with on-site Hubbard repulsion. It is shown that even within a simple Hartree -- Fock approach this interaction (which is often omitted in theoretical treatments) leads to qualitatively important effects which are highly relevant in the context of...

We investigate the structure of magnetic domain walls in a classical double exchange ferromagnet, evaluating domain wall energies and charges. Three different cases are studied: (i) a conventional smooth Bloch wall, (ii) an abrupt Ising-type wall, which is shown to have lower energy at small values of carrier concentration, and (iii) stripe wall, c...

We study a classical double exchange magnet with direct antiferromagnetic superexchange coupling, J, between the localized spins. It is shown that the destabilization of the ferromagnetic ground state with increasing J leads to phase separation; the latter always preempts the spin-wave instability (softening of the magnon spectrum). It is also foun...

An isotropic half-metallic double-exchange magnet with a direct superexchange coupling between the localized spins is studied within the spin-wave (1/S) expansion. The momentum dependence of the spin-wave spectrum (including quantum corrections) in the ferromagnetic phase at T=0 is investigated. Based on the calculated spin-wave spectrum of the can...

We construct the 1/S spin wave expansion for double exchange ferromagnets at T = 0. It is assumed that the value of Hund's rule coupling, J(H), is sufficiently large, resulting in a fully saturated, ferromagnetic half-metallic ground state. We evaluate corrections to the magnon dispersion law, and we also find that, in contrast to earlier statement...

The reorientation process in a magnetic field in two-dimensional isotropic and XY quantum Heisenberg antiferromagnets is shown to occur through the intermediate phase with unbroken continuous symmetry and constant magnetization equal to one third of the saturation value. The same reorientation process is also found in the more complicated classical...

We study the competition between ferromagnetic double exchange (DE) and direct nearest-neighbor antiferromagnetic exchange J<sub> AF </sub> in two-dimensional colossal magnetoresistance materials. Towards this end, a single site mean field theory is proposed which incorporates the hopping-mediated nature of the DE contribution. The canted state app...

In the CMR materials, ferromagnetic double exchange (DE) presumably coexists with a direct nearest-neighbour antiferromagnetic interaction. We construct a single-site mean field theory that explicitly takes into account the different nature of carrier-mediated ferromagnetism vs. Heisenberg-like superexchange. We find, in contrast to previous result...

We study correlation effects in a three-band extended Hubbard model of Cu -- O planes within the 1/N mean field approach, in the infinite U limit. We investigate the emerging phase diagram and discuss the low energy scales associated with each region. With increasing direct overlap between oxygen orbitals, $t_{pp} >0$, the solution displays a band...

We re-examine the calculation of the transverse spin-diffusion coefficient in a dilute degenerate spin-polarized Fermi gas, for the case of s-wave scattering. The special feature of this limit is that the dependence of the spin diffusion coefficient on temperature and field can be calculated explicitly with no further approximations. This exact sol...

This thesis treats two problems in many-body physics: the spin diffusion
in a spin-polarized gas and novel low- energy phenomena associated with
band crossing in a mean field theory of a three-band Hubbard model of
the cuprates. First, we present an analytical calculation of the
self-energy in the s-wave approximation for a dilute spin-polarized
Fe...

The Fermi energy is shown to be pinned near a van Hove singularity for an extended doping range in the one-band and three-band Hubbard models as a consequence of filling dependent band renormalizations.

We present a finite temperature calculation of the transverse spin-diffusion coefficient, $D_\bot$, in a dilute degenerate Fermi gas in the presence of a small external magnetic field, $H$. While the longitudinal diffusion coefficient displays the conventional low-temperature Fermi-liquid behavior, $D_\parallel \propto T^{-2}$, the corresponding re...

The "density-density" correlation function of conduction electrons in metal is investigated. It is shown, that the asymptotic behaviour of the CF depends on the shape and the local geometry of the Fermi surface. In particular, the exponent of power law which describes the damping of Friedel oscillations at large r (-4 for an isotropic Fermi gas) is...

The structure of the density-density correlation function of conduction electrons in a normal metal is determined. A relationship is established between the asymptotic behavior of the correlation function and the local geometry of the Fermi surface. Changes in the structure of the correlation function during the electron topological transition are...

We study correlation effects on the bandstructure of a three-band extended Hubbard model of the cuprates within the mean field approach to the infinite U limit. With increasing direct overlap between oxygen orbitals the solution displays a band crossing which, for an extended range of parameters, lies close to the Fermi level. The proximity of the...