arXiv subjects

K. S. Denisov

Publications and source records attributed to K. S. Denisov.

16 recordsLinked to original sources

arXiv2026

Fine structure of the cyclotron resonance in heterobilayers of proximitized graphene and transition metal dichalcogenides

A monolayer graphene and its Dirac electrons can be equipped with an enhanced spin-orbit coupling (SOC) when proximitized by other van der Waals (vdW) materials, such as transition metal dichalcogenides (TMDs). In this work we analyze the cyclotron resonance (CR) absorption of such heterobilayers at quantizing magnetic fields in the presence of proximity-induced spin interactions, including the spin-pseudospin Rashba coupling. We evaluate the spin-textured wave functions of the Landau levels and calculate the absorption spectrum paying special attention to its spin proximity induced modifications. We reveal the formation of a fine double-peak structure of the main interband CR transitions, as well as the presence of additional spin-flip absorption, the combined cyclotron resonance (CCR), centered at different resonant frequencies. The selection rules for CCRs are identified and complemented by the perturbation theory analysis. We also discuss the polarization dependence of the absorption and the proximity-induced emerging magneto-optical responses. Our theory explains the effect of proximity-induced spin interactions for Dirac electrons cyclotron resonance and points out at its experimental verifications.

cond-mat.mes-hall↗

arXiv2024

Elastic electron scattering and localization in a chain with isotopic disorder

We study elastic electron scattering and localization by ubiquitous isotopic disorder in one-dimensional systems appearing due to interaction with phonon modes localized at isotope impurities. By using a tight-binding model with intersite hopping matrix element dependent on the interatomic distance, we find mass-dependent backscattering probability by single and pairs of isotopic impurities. For the pairs, in addition to the mass, the distance between the isotopes plays the critical role. Single impurities effectively attract electrons and can produce localized weakly bound electron states. In the presence of disorder, the electron free path at positive energies becomes finite and the corresponding Anderson localization at the spatial scale greatly exceeding the distance between the impurities becomes possible.

cond-mat.dis-nn↗

arXiv2022

Spin imaging of Poiseuille flow of viscous electronic fluid

Recent progress in fabricating high-quality conductors with small densities of defects has initiated the studies of the viscous electron fluid and has motivated the search for the evidences of the hydrodynamic regime of electron transport. In this work we come up with the spin imaging technique allowing us to attest to the emergence of electron hydrodynamic flows. Based on numerical calculations we demonstrate that the injected electron spin density is inhomogeneous across the channel when the viscous electron fluid forms the Poiseuille flow. We also argue that the Hanle curves at different positions across the channel acquire relative phase shifts resulting from the variation of the electron drift velocity in inhomogeneous hydrodynamic flows. The studied effects can be employed to evidence and study the viscous electron fluid non-invasively.

cond-mat.mes-hall↗

arXiv2021

Electric field effect on electron gas spins in two-dimensional magnets with strong spin-orbit coupling

The recent rise of material platforms combining magnetism and two-dimensionality of mobile carriers reveals a diverse spectrum of spin-orbit phenomena and stimulates its ongoing theoretical discussions. In this work we use the density matrix approach to provide a unified description of subtle microscopic effects governing the electron gas spin behavior in the clean limit upon electric perturbations in two-dimensional magnets with strong spin-orbit coupling. We discuss that an inhomogeneity of electrostatic potential generally leads to the electron gas spin tilting with the subsequent formation of equilibrium skyrmion-like spin textures and demonstrate that several microscopic mechanisms of 2DEG spin response are equally important for this effect. We analyze the dynamics of 2DEG spin upon an oscillating electric field with a specific focus on the emergent electric dipole spin resonance. We address the resonant enhancement of magneto-optical phenomena from the spin precession equation perspective and discuss it in terms of the resonant spin generation. We also clarify the connection of both static and dynamic spin phenomena arising in response to a scalar perturbation with the electronic band Berry curvature.

cond-mat.mes-hall↗

arXiv2021

Colossal topological Hall effect at the transition between isolated and lattice-phase interfacial skyrmions

The topological Hall effect is used extensively to study chiral spin textures in various materials. However, the factors controlling its magnitude in technologically-relevant thin films remain uncertain. Using variable temperature magnetotransport and real-space magnetic imaging in a series of Ir/Fe/Co/Pt heterostructures, here we report that the chiral spin fluctuations at the phase boundary between isolated skyrmions and a disordered skyrmion lattice result in a power-law enhancement of the topological Hall resistivity by up to three orders of magnitude. Our work reveals the dominant role of skyrmion stability and configuration in determining the magnitude of the topological Hall effect.

cond-mat.mes-hall↗

arXiv2021

Anisotropic magnetoresistance and memory effect in bulk systems with extended defects

Memory effects can have a profound impact on the resistivity of semiconductor systems, resulting in giant negative magnetoresistance and MIRO phenomena. This work opens the discussion of the memory effects in 3D conducting systems featured by the presence of the extended one-dimensional defects, such as screw dislocations or static charge stripes. We demonstrate that accounting for the memory effect, that is the capture of electrons on collisionless spiral trajectories winding around extended defects, leads to the strong negative magnetoresistance in case when the external magnetic field direction becomes parallel to the defects axis. This effect gives rise to a significant magnetoresistance anisotropy already for an isotropic Fermi surface and no spin-orbit effects. The proposed resistivity feature can be used to detect one-dimensional scattering defects in these systems.

cond-mat.mes-hall↗

arXiv2020

Fingerprints of the electron skew-scattering on paramagnetic impurities in semiconductor systems

In this paper we argue that the electron skew-scattering on paramagnetic impurities in non-magnetic systems, such as bulk semiconductors, possesses a remarkable fingerprint allowing to differentiate it directly from other microscopic mechanisms of the emergent Hall response. We demonstrate theoretically that the exchange interaction between the impurity magnetic moment and mobile electrons leads to the emergence of an electric Hall current persisting even at zero electron spin polarization. We describe two microscopic mechanisms behind this effect, namely the exchange interaction assisted skew-scattering and the conversion of the SHE induced transverse spin current to the charge one owing to the difference between the spin-up and spin-down conductivities. We propose an essentially all-electric scheme based on a spin-injection ferromagnetic-semiconductor device which allows one to reveal the effect of paramagnetic impurities on the Hall phenomena via the detection of the spin polarization independent terms in the Hall voltage.

cond-mat.other↗

arXiv2020

Theory of an electron asymmetric scattering on skyrmion textures in two-dimensional systems

We discuss in details the electron scattering pattern on skyrmion-like magnetic textures in two-dimensional geometry. The special attention is focused on analyzing the scattering asymmetry, which is a precursor of the topological Hall effect. We present analytical results valid for the limiting regimes of strong and weak coupling, we also describe the numerical scheme that gives access to the exact solution of the scattering problem. Based on the numerical computations we investigate the properties of the asymmetric scattering for an arbitrary magnitude of the interaction strength and the topology of a magnetic texture. We analyze in details the conditions when the topological charge of a magnetic texture is indeed essential for the appearance of the Hall response. We also describe how the electron scattering asymmetry is modified due to an additional short-range impurity located inside a magnetic skyrmion.

cond-mat.mes-hall↗

arXiv2019

Chiral spin structure of electron gas in systems with magnetic skyrmions

The theoretical study considers chiral spin texture induced in a 2D electron gas (2DEG) by magnetic skyrmions. We calculate the electron gas spin density as a linear response to the exchange interaction between the 2DEG and the magnetization field of a magnetic skyrmion. Two physically distinct regimes occur. When the size of the skyrmion is larger than the inverse Fermi wavevector $k_F^{-1}$, the spin density response follows the magnetization profile of the skyrmion. In the opposite case of a small skyrmion the emerging spin structure of 2DEG has a characteristic size of $k_F^{-1}$ and the response becomes non-local, it can be viewed as chiral Friedel oscillations. At that, the emerging spin structure of the oscillations appears to be more complex than that of the skyrmion itself.

cond-mat.mes-hall↗

arXiv2019

Chiral spin ordering of electron gas in solids with broken time reversal symmetry

In this work we manifest that an electrostatic disorder in conducting systems with broken time reversal symmetry universally leads to a chiral ordering of the electron gas giving rise to skyrmion-like textures in spatial distribution of the electron spin density. We describe a microscopic mechanism underlying the formation of the equilibrium chiral spin textures in two-dimensional systems with spin-orbit interaction and exchange spin splitting. We have obtained analytical expressions for spin-density response functions and have analyzed both local and non-local spin response to electrostatic perturbations for systems with parabolic-like and Dirac electron spectra. With the proposed theory we come up with a concept of controlling spin chirality by electrical means.

cond-mat.mes-hall↗

arXiv2019

Weak Localization in Systems with Chiral Spin Textures and Skyrmion Crystals

Theory of interference-induced quantum corrections to conductivity is developed for two dimensional systems with chiral spin textures including skyrmions. The effect of exchange interaction between electrons and spin textures on weak localization of electronic waves is studied. The spin dephasing rates are calculated as functions of the spin texture size. The anomalous magnetoresistance is shown to be governed by the size and magnetization spatial distribution of the spin textures. The effect of average magnetization-induced spin splitting on weak localization is analyzed. The sign-alternating weak-antilocalization magnetoresistance is demonstrated for skyrmion crystals. We argue that analysis of the low-field magnetoresistance serves as an independent tool for an experimental detection of chiral spin textures and, in particular, skyrmions.

cond-mat.mes-hall↗

arXiv2018

General theory of topological Hall effect in systems with chiral spin textures

We present a consistent theory of the topological Hall effect (THE) in 2D magnetic systems with disordered array of chiral spin textures, such as magnetic skyrmions. We focus on the scattering regime when the mean-free path of itinerant electrons exceeds the spin texture size, and THE arises from the asymmetric carrier scattering on individual chiral spin textures. We calculate the resistivity tensor on the basis of the Boltzmann kinetic equation taking into account the asymmetric scattering on skyrmions via the collision integral. Our theory describes both the adiabatic regime, when THE arises from a spin Hall effect and the non-adiabatic scattering when THE is due to purely charge transverse currents. We analyze the dependence of THE resistivity on a chiral spin texture structure,as well as on material parameters. We discuss the crossover between spin and charge regimes of THE driven by the increase of skyrmion size, the features of THE due to the variation of the Fermi energy, and the exchange interaction strength; we comment on the sign and magnitude of THE

cond-mat.mes-hall↗

arXiv2018

Topological Hall effect for electron scattering on skyrmions in external magnetic field

We consider topological Hall effect (THE) in thin ferromagnetic films due to electron scattering on magnetic skyrmions in the presence of the relatively strong external magnetic field. We account for the effect of the magnetic field on a skyrmion structure and describe the hallmarks of THE differentiating it from ordinary and anomalous Hall effects. We have found that, although in typical ferromagnets the variation of magnetic field in the range 1-5 T substantially affects the skyrmion size, THE changes rather weakly remaining quite robust. Therefore, the magnitude of THE is primarily determined by the skyrmions sheet density $n_{sk}$, being comparable to the magnitude of the ordinary Hall effect (OHE) at $n_{sk}=10^{11}$ cm$^{-2}$. The sign of THE is opposite to that of OHE for skyrmions with positive vorticity, while for antiskyrmions the signs are the same.

cond-mat.mes-hall↗

arXiv2018

Hall effect driven by non-collinear magnetic polarons in diluted magnetic semiconductors

In this letter we develop the theory of Hall effect driven by non-collinear magnetic textures (topological Hall effect - THE) in diluted magnetic semiconductors (DMS). We show that a carrier spin-orbit interaction induces a chiral magnetic ordering inside a bound magnetic polaron (BMP). The inner structure of non-collinear BMP is controlled by the type of spin-orbit coupling, allowing to create skyrmion- (Rashba) or antiskyrmion-like (Dresselhaus) configurations. The asymmetric scattering of itinerant carriers on polarons leads to the Hall signal which exists in weak external magnetic fields and low temperatures. We point out that DMS-based systems allow one to investigate experimentally the dependence of THE both on a carrier spin polarization and on a non-collinear magnetic texture shape.

cond-mat.mes-hall↗

arXiv2017

A nontrivial crossover in topological Hall effect regimes

We propose a new theory of the topological Hall effect (THE) in systems with chiral magnetization vortices such as magnetic skyrmions. We solve the problem of electron scattering on a magnetic skyrmion exactly, for an arbitrary strength of exchange interaction and the skyrmion size. We report the existence of different regimes of THE and resolve the apparent contradiction between the adiabatic Berry phase theoretical approach and the perturbation theory for THE. We traced how the topological charge Hall effect transforms into the spin Hall effect upon varying the exchange interaction strength or the skyrmion size. This transformation has a nontrivial character: it is accompanied by an oscillating behavior of both charge and spin Hall currents. This hallmark of THE allows one to differentiate the chirality driven contribution to Hall response in the experiments.

cond-mat.mes-hall↗

arXiv2016

Scattering on magnetic skyrmion in the non-adiabatic approximation

We present a theory of electron scattring on a magnetic skyrmion for the case when exchange interaction is moderate so that adiabatic approximation and Berry phase approach is not applicable. The theory explains the appearance of a topological Hall current in the systems with magnetic skyrmions, of a special importance its applicability to dilute magnetic semiconductors with a weak exchange interaction.

cond-mat.mes-hall↗