arXiv subjects

Yu. A. Kolesnichenko

Publications and source records attributed to Yu. A. Kolesnichenko.

At least 19 recordsLinked to original sources

arXiv2026

Specific features of the magnetic-field dependences of electrical resistivity in Bi--Mn solid solutions with low Mn content

For the first time, the field dependences of the magnetoresistance of a textured polycrystalline Bi$_{88.08}$Mn$_{11.92}$ sample were investigated in the $H \perp I$ and $H \parallel I$ configurations, and the results were compared with those previously obtained for the solid solution Bi$_{95.69}$Mn$_{3.69}$Fe$_{0.62}$ with a lower manganese concentration. It was demonstrated that the magnetoresistance field dependencies for Bi$_{88.08}$Mn$_{11.92}$ differ significantly from those of Bi$_{95.69}$Mn$_{3.69}$Fe$_{0.62}$ below 100 K, becoming nearly identical as the temperature approaches room temperature. It was established that the maximum relative magnetoresistance values for Bi$_{88.08}$Mn$_{11.92}$ are observed at a magnetic field of 90 kOe and a temperature of 100 K in both the $H \perp I$ and $H \parallel I$ configurations, amounting to 3170\% and 380\%, respectively. These values are significantly lower than those previously reported for the solid solution containing less manganese (Bi$_{95.69}$Mn$_{3.69}$Fe$_{0.62}$), which were 3877\% and 742\%, respectively. Analysis of the results indicates that differences in field dependence among the studied materials are associated with varying amounts of magnetic $α$-BiMn. The anomalous magnetoresistance behavior, as compared with that of pure bismuth, is attributed to the influence of internal magnetism on electrical transport within the bismuth matrix of the studied solid solutions.

cond-mat.mtrl-sci↗

arXiv2025

Study of fluctuation conductivity in YBa$_2$Cu$_3$O$_7$--$δ$ films in strong magnetic fields

We report the effect of the \emph{ab}-plane magnetic field $B$ up to $8\,\mathrm{T}$ on the resistivity $ρ(T)$ and fluctuation conductivity $σ'(T)$ in YBa$_2$Cu$_3$O$_{7-δ}$ thin films. As expected, up to $\sim 2.5\,\mathrm{T}$ the magnetic field monotonously increases $ρ$, the width of the resistive transition $ΔT_c$, and the coherence length along the $c$ axis, $ξ_c(0)$, but decreases both $T_c$ and the range of superconducting (SC) fluctuations $Δ_{\mathrm{fl}}$. The fluctuation conductivity exhibits a crossover at characteristic temperature $T_0$ from the 3D Aslamazov--Larkin (AL) theory near $T_c$ to the 2D fluctuation theory of Maki--Thompson (MT). However, at $B = 3\,\mathrm{T}$, the MT term is completely suppressed, and above $T_0$ $σ'(T)$ is unexpectedly described by the fluctuation contribution of 2D AL, suggesting the formation of a two-dimensional vortex lattice in the film under the action of a magnetic field. At the same time, $ΔT_{\mathrm{fl}}$ sharply increases by a factor of about 7, and $ξ_c(0)$ demonstrates a very unusual dependence on $T_c$ when $B$ increases above $3\,\mathrm{T}$. Our results demonstrate the possibility of the formation of a vortex state in YBCO and its evolution with increasing $B$.

cond-mat.supr-con↗

arXiv2025

Edge states at the boundary of graphene-like and Lieb lattices

Properties of the boundary of two conductors in a quantizing magnetic field are studied: with conventional Dirac charge carriers and so-called pseudospin-1 fermions, which are realized in graphene-like and Lieb lattices respectively. It is shown that edge states arise that relate the properties of conductors to the trivial and nontrivial Berry phase. These edge states lead to the appearance of a characteristic series of root features in the density of states.

cond-mat.mes-hall↗

arXiv2025

Changes in the coercivity fields of magnetoresistance hysteresis loops under the influence of a spin-polarized current

Using the example of a pressed sample consisting of chromium dioxide nanoparticles coated with insulating shells, we study the relationship between the electronic transport system and magnetic subsystem in granular spin-polarized metals. It is shown that the spin-polarized tunneling transport current can affect the coercivity fields of the percolation cluster formed in the sample with decreasing temperature.

cond-mat.mes-hall↗

arXiv2024

Evolution of the pseudogap temperature dependence in YBa$_2$Cu$_3$O$_{7-δ}$ films under the influence of a magnetic field

The evolution of the temperature dependence of pseudogap $Δ$*(T) in optimally doped (OD) YBa$_2$Cu$_3$O$_{7-δ}$ (YBCO) films with $T_{c}$ = 88.7 K under the influence of a magnetic field $B$ up to 8 T has been studied in detail. It has been established that the shape of $Δ$*(T) for various $B$ over the entire range from the pseudogap opening temperature $T$* to $T_{01}$, below which superconducting fluctuations occur, has a wide maximum at the BEC-BCS crossover temperature $T_{pair}$, which is typical for OD films and untwinned YBCO single crystals. $T$* was shown to be independent on $B$, whereas $T_{pair}$ shifts to the low temperature region along with increase of $B$, while the maximum value of $Δ$*($T_{pair}$) remains practically constant regardless of $B$. It was revealed that as the field increases, the low-temperature maximum near the 3D-2D transition temperature $T_{0}$ is blurred and disappears at $B$ > 5 T. Moreover, above the Ginzburg temperature $T_{G}$, which limits superconducting fluctuations from below, at $B$ > 0.5 T, a minimum appears on $Δ$*(T) at $T_{min}$, which becomes very pronounced with a further increase in the field. As a result, the overall value of $Δ$*(T) decreases noticeably most likely due to pair-breaking affect of a magnetic field. A comparison of $Δ$*(T) near $T_{c}$ with the Peters-Bauer theory shows that the density of fluctuating Cooper pairs actually decreases from < > $\approx$ 0.31 at $B$ = 0 to < > $\approx$ 0.28 in the field 8 T. The observed behavior of $Δ$*(T) around $T_{min}$ is assumed to be due to the influence of a two-dimensional vortex lattice created by the magnetic field, which prevents the formation of fluctuating Cooper pairs near $T_{c}$.

cond-mat.supr-con↗

arXiv2023

Effects of annealing on the fluctuation conductivity and pseudogap in slightly doped $HoBa_2Cu_3O_{7-δ}$ single crystals

The effect of annealing at room temperature on the fluctuation conductivity (FLC) $σ^\prime(T)$ and pseudogap (PG) $Δ^*(T)$ in the basal ab plane of $ReBa_2Cu_3O_{7-δ}$ (Re = Ho) single crystals with a lack of oxygen has been studied. It is shown that at all stages of annealing, the FLC near $T_c$ can be described by the Aslamazov$-$Larkin and Maki$-$Thompson fluctuation theories, demonstrating a 3D$-$2D crossover with increasing temperature. The crossover temperature $T_0$ was used to determine the coherence length along the $c$-axis, $ξ_c(0)$=2.82 A. At the inter-mediate stage of annealing, an anomalous increase in 2D FLC was revealed, which is associated with the influence of uncompensated magnetic moments in $HoBa_2Cu_3O_{7-δ}$ (HoBCO): $μ_{eff, Ho}$=9.7$μ_{B}$. For the quenched sample S1, the temperature dependence of the PG has a shape typical of single crystals with a large number of defects. However, $Δ^*(T)$ has two small additional maxima at high temperature, which is a feature of HoBCO single crystals with pronounced twins and indicates the two-phase nature of the sample. Upon annealing, the shape of $Δ^*(T)$ noticeably changes, very likely due to an increase in the magnetic interaction (sample S2). More important is the change in the slope of the data at high temperatures, which has become about 3.5 times steeper. The ordering of the oxygen distribution due to the diffusion process during annealing somewhat compensates for the influence of magnetic interaction. Interestingly, the slope turns out to be the same as for FeAs-based superconductors, suggesting the possibility of the existence of spin density waves in HoBCO in the PG state.

cond-mat.supr-con↗

arXiv2022

Temperature dependence of upper critical fields and coherence lengths for optimally-doped $YBa_2Cu_3O_{7-δ}$ thin films

We report the comprehensive comparative analysis of the upper critical magnetic fields $μ_{0}H_{c2}(0)$ obtained within Ginzburg-Landau and Werthamer-Helfand-Hohenberg theories for optimally-doped $YBa_2Cu_3O_{7-δ}$ thin films. For different orientations of the magnetic field, our calculations give 638 and 153 T for $μ_{0}H_{c2}(0)$, H || ab and $μ_{0}H_{c2}(0)$, H || c, respectively, when using $H_{c2}(0)$. For the first time, the temperature dependences of coherence lengths $ξ_{ab}(T)$ and $ξ_{c}(T)$ within proposed theories were determined using 50 and 90% criteria of the normal state resistivity value $ρ_{N}$. The Ginzburg-Landau 0.9$ρ_{N}$ approach gives $ξ_{ab}(0)$=11.8 A, and $ξ_{c}(0)$=3.0 A which are in a good agreement with literature data. The implications of very short coherence lengths in HTSCs are discussed.

cond-mat.supr-con↗

arXiv2019

Friedel oscillations in 2D electron gas from spin-orbit interaction in a parallel magnetic field

Effects associated with the interference of electron waves around a magnetic point defect in two-dimensional electron gas with combined Rashba-Dresselhaus spin-orbit interaction in the presence of a parallel magnetic field are theoretically investigated. The effect of a magnetic field on the anisotropic spatial distribution of the local density of states and the local density of magnetization is analyzed. The existence of oscillations of the density of magnetization with scattering by a non-magnetic defect and the contribution of magnetic scattering (accompanied by spin-flip) in the local density of electron states are predicted.

cond-mat.mes-hall↗

arXiv2019

Magnetic-field-driven topological transitions in non-centrally-symmetric energy spectrum of 2D electron gas with Rashba-Dresselhaus spin-orbit interaction

Spin orbit interaction (SOI) having a complicated energy spectrum with a conical point and four critical points are promising candidates to observe electron topological transitions. In the present paper we have investigated the evolution of the electron spectrum and isoenergetic contours under the influence of parallel magnetic field. General formulas for energies of critical points for arbitrary values of SOI constants and magnetic field are found. The existence of critical magnetic fields at which a number of critical points is changed has been predicted. The magnetic field driving topological Lifshitz transitions in the geometry of isoenergetic contours have been studied. Van Hove's singularities in the electron density of states are calculated. The obtained results can be used for theoretical investigations of different electron characteristics of such 2D systems.

cond-mat.mes-hall↗

arXiv2018

Exact and quasiclassical Green's functions of two-dimensional electron gas with Rashba-Dresselhaus spin-orbit interaction in parallel magnetic field

New exact and asymptotical results for the one particle Green's function of 2D electrons with combined Rashba - Dresselhaus spin - orbit interaction in the presence of in-plane uniform magnetic field are presented. A special case that allows an exact analytical solution is also highlighted. To demonstrate the advantages of our approach we apply the obtained Green's function to calculation of electron density and magnetization

cond-mat.mes-hall↗

arXiv2016

Quantum interference patterns around magnetic impurities in a 2D electron gas with strong Rashba spin-orbit interaction

Explicit dependencies of the local density of states and the magnetization local density of states have been obtained around magnetic point defects in a two-dimensional electron gas with Rashba spin-orbit interaction . The expressions are given in the Born approximation for arbitrary magnitude and orientation of the defect magnetic moment, and for arbitrary size of the constant of spin-orbit interaction alpha/. On the basis of our asymptotically exact formulas a procedure for the determination of the constant alpha/ in STM experiments is proposed. The novel analytical results are compared with the numerical and approximate results of previous work. At variance with earlier work we find that that magnetic scattering in the presence of spin-orbit interaction does not modify the local density of states and that the spin texture resulting from in-plain orientation of the defect magnetic moment, and elastic scattering, is not a purely in-plane spin texture.

cond-mat.mes-hall↗

arXiv2013

Fermi surface contours obtained from STM images around surface point defects

We present a theoretical analysis of the standing wave patterns in STM images, which occur around surface point defects. We consider arbitrary dispersion relations for the surface states and calculate the conductance for a system containing a small-size tunnel contact and a surface impurity. We find rigorous theoretical relations between the interference patterns in the real-space STM images, their Fourier transforms and the Fermi contours of two-dimensional electrons. We propose a new method for reconstructing Fermi contours of surface electron states, directly from the real-space STM images around isolated surface defects.

cond-mat.mes-hall↗

arXiv2012

Conductance of a STM contact on the surface of a thin film

The conductance of a contact, having a radius smaller than the Fermi wave length, on the surface of a thin metal film is investigated theoretically. It is shown that quantization of the electron energy spectrum in the film leads to a step-like dependence of differential conductance G(V) as a function of applied bias eV. The distance between neighboring steps in eV equals the energy level spacing due to size quantization. We demonstrate that a study of G(V) for both signs of the voltage maps the spectrum of energy levels above and below Fermi surface in scanning tunneling experiments.

cond-mat.mes-hall↗

arXiv2011

Mixed (1D-2D) quantum electron transport in percolating gold film

The gold film (mean thickness $\approx$ 3.5 nm) was condensed in high vacuum at temperature 70 K on single-crystal sapphire substrate. The transport properties of the film at low temperature reveal simultaneously indications of 1D and 2D quantum interference effects of weak localization and electron-electron interaction. It is shown that this behavior is determined by inhomogeneous electron transport at the threshold of thickness-controlled metal-insulator transition.

cond-mat.mes-hall↗

arXiv2010

Quantum interference effects in a system of two tunnel point-contacts in the presence of single scatterer: simulation of a double-tip STM experiment

The conductance of systems containing two tunnel point-contacts and a single subsurface scatterer is investigated theoretically. The problem is solved in the approximation of s-wave scattering giving analytical expressions for the wave functions and for the conductance of the system. Conductance oscillations resulting from the interference of electron waves passing through different contacts and their interference with the waves scattered by the defect are analyzed. The prospect for determining the depth of the impurity below the metal surface by using the dependence of the conductance as a function of the distance between the contacts is discussed. It is shown that the application of an external magnetic field results in Aharonov-Bohm type oscillations in the conductance, the period of which allows detection of the depth of the defect in a double tip STM experiment.

cond-mat.mes-hall↗

arXiv2010

Electron phenomena in layered conductors

The quasi-two-dimensional nature of the charge carriers energy spectrum in layered conductors leads to specific effects in an external magnetic field. The magnetoresistance of layered conductors in a wide range of strong magnetic fields directed in the plane of the layers can increase proportionally to a magnetic field value. The electromagnetic impedance and the sound attenuation rate depend essentially on the polarization of normal to the layers. Propagation of electromagnetic and acoustic waves in these conductors involves virtually all charge carriers in the transfer of acoustic pulses and electromagnetic field spikes to the bulk of the conductor. The orbits of Fermi electrons in a magnetic field are virtually indistinguishable, which allows the inclusion of large number of conduction electrons in the formation of peculiar oscillatory and resonant effects which are absent in the case of ordinary metals. Investigation of these effects introduce the possibilities for detailed study of the dissipative processes in electron systems of layered conductors and the charge carriers energy spectrum. Point contact investigations of layered metals allow us to obtain the information about electron and phonon spectra. The electron focusing signal and the point contact spectrum are extremely sensitive to the orientation of the magnetic field vector $\bs{H}$ in relation to the layers with a high electrical conductivity. The values of $\bs{H}$ for which the electron focusing signal has peaks can be used for determining velocities and extremal diameters for the open Fermi surface. The dependence of the point contact spectra on the magnitude and the relaxation of electrons at various types of phonon excitations.

cond-mat.stat-mech↗

arXiv2010

Kinetic phenomena in metallic multilayers

A series of kinetic phenomena in metallic multilayers has been considered. The kinetic properties of multilayers differ essentially from the properties of both massive metals and thin films. One of the main reasons of that is the influence of electron interaction of electrons with interfaces between layers. From one hand, this interaction leads to the additional electron scattering and conductivity of multilayer may be noticeably less than specific conductivities of composing metals. From the other hand, the electron reflection from interfaces in a strong magnetic field may results in considerable increasing of conducting properties in consequence of the static skin effect. Due to changing of electron trajectories after collisions with interfaces new types of periodic motion in the magnetic field and therefore new size and resonance phenomena in high frequency fields appear. In thin normal layers on the superconducting substrate, changing of trajectories is due to Andreev reflection and resonance effects, which do not exist in normal multilayers, films, and bulk monocrystals, take place. In multilayers consisting of ferromagnetic and nonmagnetic metals, the internal magnetic field in ferromagnetic layers must be taken into account, if the Larmor radius in this field is comparable with the layer thickness. Because of the mutual diffusion of metals, the kinetic coefficients of multilayers are changed in time. The investigation of this changing may be used for determination of diffusion coefficient for the bulk and grain-boundary diffusion. The effects, which have been analyzed theoretically in this review, can be used for the obtaining information on the electron interaction with interfaces in conducting multilayers.

cond-mat.stat-mech↗

arXiv2010

Theory of oscillations in the STM conductance resulting from subsurface defects (Review Article)

In this review we present recent theoretical results concerning investigations of single subsurface defects by means of a scanning tunneling microscope (STM). These investigations are based on the effect of quantum interference between the electron partial waves that are directly transmitted through the contact and the partial waves scattered by the defect. In particular, we have shown the possibility imaging the defect position below a metal surface by means of STM. Different types of subsurface defects have been discussed: point-like magnetic and non-magnetic defects, magnetic clusters in a nonmagnetic host metal, and non-magnetic defects in a s-wave superconductor. The effect of Fermi surface anisotropy has been analyzed. Also, results of investigations of the effect of a strong magnetic field to the STM conductance of a tunnel point contact in the presence of a single defect has been presented.

cond-mat.mes-hall↗