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Ivan Iorsh

Publications and source records attributed to Ivan Iorsh.

At least 37 records · Page 2Linked to original sources
arXiv2023

Bulk ReSe2: record high refractive index and biaxially anisotropic material for all-dielectric nanophotonics

We show that bulk rhenium diselenide, ReSe2 is characterized by record high value of the refractive index exceeding 5 in near-infrared frequency range. We use back focal plane reflection spectroscopy to extract the components of the ReSe2 permittivity tensor and reveal its extreme biaxial anisotropy. We also demonstrate the good agreement between the experimental data and the predictions of the density functional theory. The combination of the large refractive index and giant optical anisotropy makes ReSe2 a perspective material for all-dielectric nanophotonics in the near-infrared frequency range.

cond-mat.mes-hall↗
arXiv2022

Quartic asymmetric exchange for two-dimensional ferromagnets with trigonal prismatic symmetry

We suggest a possible origin of noncollinear magnetic textures in ferromagnets (FMs) with the $D_{3h}$ point group symmetry. The suggested mechanism is different from the Dzyaloshinskii-Moriya interaction (DMI) and its straightforward generalizations. The considered symmetry class is important because a large fraction of all single-layer intrinsic FMs should belong to it. In particular, so does a monolayer Fe$_3$GeTe$_2$. At the same time, DMI vanishes identically in materials described by this point group, in the continuous limit. We use symmetry analysis to identify the only possible contribution to the free energy density in two dimensions that is of the fourth order with respect to the local magnetization direction and linear with respect to its spatial derivatives. This contribution predicts long-range conical magnetic spirals with both the average magnetization and the average chirality dependent on the spiral propagation direction. We relate the predicted spirals to a recent experiment on Fe$_3$GeTe$_2$. Finally, we demonstrate that, for easy-plane materials, the same mechanism may stabilize bimerons.

cond-mat.mes-hall↗
arXiv2022

Cavity induced chiral edge currents and spontaneous magnetization in two-dimensional electron systems

We consider a laterally confined two-dimensional electron gas (2DEG), placed inside a gyrotropic cavity. Splitting of the circularly polarized electromagnetic modes leads to the emergence of the ground state spontaneous magnetization, anomalous Hall effect and chiral edge currents in 2DEG. We examine the dependence of the magnetization and edge current density on the system size for two particular cases of the confining potential: infinite wall and parabolic potentials. We show that paramagnetic and diamagnetic contributions to the edge currents have qualitatively different dependence on the system size. These findings pave the route to the design quantum electrodynamic engineering of the material properties of the mesoscopic electron systems.

cond-mat.mes-hall↗
arXiv2022

Brightening of a dark monolayer semiconductor via strong light-matter coupling in a cavity

Engineering the properties of quantum materials via strong light-matter coupling is a compelling research direction with a multiplicity of modern applications. Those range from modifying charge transport in organic molecules, steering particle correlation and interactions, and even controlling chemical reactions. Here, we study the modification of the material properties via strong coupling and demonstrate an effective inversion of the excitonic band-ordering in a monolayer of WSe2 with spin-forbidden, optically dark ground state. In our experiments, we harness the strong light-matter coupling between cavity photon and the high energy, spin-allowed bright exciton, and thus creating two bright polaritonic modes in the optical bandgap with the lower polariton mode pushed below the WSe2 dark state. We demonstrate that in this regime the commonly observed luminescence quenching stemming from the fast relaxation to the dark ground state is prevented, which results in the brightening of this intrinsically dark material. We probe this effective brightening by temperature-dependent photoluminescence, and we find an excellent agreement with a theoretical model accounting for the inversion of the band ordering and phonon-assisted polariton relaxation.

cond-mat.mes-hall↗
arXiv2021

Localized vibrational modes in waveguide quantum optomechanics with spontaneously broken PT symmetry

We study theoretically two vibrating quantum emitters trapped near a one-dimensional waveguide and interacting with propagating photons. We demonstrate, that in the regime of strong optomechanical interaction the light-induced coupling of emitter vibrations can lead to formation of spatially localized vibration modes, exhibiting parity-time (PT ) symmetry breaking. These localized vibrations can be interpreted as topological defects in the quasiclassical energy spectrum.

quant-ph↗
arXiv2021

Quantum spin compass models in 2D electronic topological metasurfaces

We consider a metasurface consisting of a square lattice of cylindrical antidots in a two-dimensional topological insulator (2DTI). Each antidot supports a degenerate Kramer's pair of eigenstates formed by the helical topological edge states. We show that the on-site Coulomb repulsion leads to the onset of the Mott insulator phase in the system in a certain range of experimentally relevant parameters. Intrinsic strong spin-orbit coupling characteristic for the 2DTI supports a rich class of the emerging low-energy spin Hamiltonians which can be emulated in the considered system, which makes it an appealing solid state platform for quantum simulations of strongly correlated electron systems.

cond-mat.mes-hall↗
arXiv2021

Vacuum anomalous Hall effect in gyrotropic cavity

We consider the ground state of an electron gas embedded in a quantum gyrotropic cavity. We show that the light-matter interaction leads to a nontrivial topology of the many-body electron-photon wave function characterized by a nonzero Berry curvature. Physically, the latter manifests as the anomalous Hall effect, appearance of equilibrium edge/surface currents and orbital magnetization induced by vacuum fluctuations. Remarkably, closed analytical expressions for the anomalous Hall conductivity and macroscopic magnetization are obtained for the interacting many-body case.

cond-mat.mes-hall↗
arXiv2020

Chiral waveguide optomechanics: first order quantum phase transitions with $\mathbb{Z}_3$ symmetry breaking/

We present a direct mapping between the quantum optomechanical problem of the atoms harmonically trapped in the vicinity of a chiral waveguide and a generalized quantum Rabi model and discuss the analogy between the self-organization of atomic chains in photonic structures and Dicke-like quantum phase transitions in the ultrastrong coupling regime. We extend the class of the superradiant phase transitions for the systems possessing $\mathbb{Z}_3$ rather than parity $\mathbb{Z}_2$ symmetry and demonstrate the emergence of the multicomponent Schrodinger cat ground states in these systems.

cond-mat.mes-hall↗
arXiv2020

Waveguide quantum optomechanics: parity-time phase transitions in ultrastrong coupling regime

We develop a rigorous theoretical framework for interaction-induced phenomena in the waveguide quantum electrodynamics (QED) driven by mechanical oscillations of the qubits. Specifically, we predict that the simplest set-up of two qubits, harmonically trapped over an optical waveguide, enables the ultrastrong coupling regime of the quantum optomechanical interaction. Moreover, the combination of the inherent open nature of the system and the strong optomechanical coupling leads to emerging parity-time (\PT) symmetry, quite unexpected for a purely quantum system without artificially engineered gain and loss. The $\mathcal{PT}$ phase transition drives long-living subradiant states, observable in the state-of-the-art waveguide QED setups.

cond-mat.mes-hall↗
arXiv2020

High refractive index and extreme biaxial optical anisotropy of rhenium diselenide for applications in all-dielectric nanophotonics

We establish simple quantitative criterium for the search of new dielectric materials with high values of the refractive index in the visible range. It is demonstrated, that for light frequencies below the band gap the latter is determined by the dimensionless parameter $η$ calculated as the ratio of the sum of the widths of conduction and valence bands and the band gap. Small values of this parameter, which can be achieved in materials with almost flat bands, lead to dramatic increase of the refractive index. We illustrate this rule with a particular example of rhenium dichalcogenides, for which we perform ab-initio calculations of the band structure and optical susceptibility and predict the values of the refractive index > 5 in a wide frequency range around 1 eV together with compratively low losses. Our findings open new perspectives in the search for the new high-index/low loss materials for all-dielectric nanophotonics.

cond-mat.mes-hall↗
arXiv2020

Broadband enhancement of second harmonic generation at the domain walls of magnetic topological insulators

We show that the second harmonic generation (SHG) is enhanced in the chiral one-dimensional electron currents in a broad frequency range. The origin of the enhancement is two-fold: first, the linear dispersion of the current and the associated plasmonic mode as well as the quasi-linear dispersion of plasmon-polariton result in the lift of the phase matching condition. Moreover, the strong field localization leads to the further increase of the SHG in the structure. The results suggest that the chiral currents localized at the domain walls of magnetic topological insulators can be an efficient source of second harmonic signal in the terahertz frequency range.

cond-mat.mes-hall↗
arXiv2019

Plasmon-polariton from a helical state in Dirac magnet

Optical field interacting with a topologically protected one-dimensional helical state is shown to support a one-dimensional plasmon-polariton that is characterized by a non-linear dispersion. In a two-dimensional Dirac magnet these electro-optical excitations are confined to domain walls, thus, offering a possibility to manipulate quantum optical states by altering magnetic domain configurations. An exact spectral equation for such a topological plasmon-polariton is derived.

cond-mat.mes-hall↗
arXiv2018

Resonant edge-site pumping of polaritonic Su-Schrieffer-Heeger lattices

We have theoretically investigated Su-Schrieffer-Heeger chains modelled as optical lattices (OL) loaded with exciton-polaritons. The chains have been subject to the resonant pumping of the edge site and shaken in either adiabatic or high-frequency regime. The topological state has been controlled by the relative phases of the lasers constructing the OL. The dynamic problem of the occupation of the lattice sites and eigenstates has been semi-classically solved. Finally, the analysis of the occupation numbers evolution has revealed that gapless, topologically trivial and non-trivial chain configurations demonstrate perceptible behaviour from both qualitative (occupation pattern) and quantitative (total occupation) points of view.

cond-mat.mes-hall↗
arXiv2018

Resonant spin wave excitation in magnetoplasmonic bilayers by short laser pulses

In magnetically ordered solids a static magnetic field can be generated by virtue of the transverse magneto-optical Kerr effect (TMOKE). Moreover, the latter was shown to be dramatically enhanced due to the optical excitation of surface plasmons in nanostructures with relatively small optical losses. In this paper we suggest a new method of resonant optical excitations in a prototypical bilayer composed of noble metal (Au) with grating and a ferromagnet thin film of yttrium iron garnet (YIG) via frequency comb. Based on magnetization dynamics simulations we show that for the frequency comb with the parameters, chosen in resonant with spin-wave excitations of YIG, TMOKE is drastically enhanced, hinting towards possible technological applications in the optical control of spintronics systems.

cond-mat.mes-hall↗
arXiv2017

Topological edge state engineering with high-frequency electromagnetic radiation

We outline here how strong light-matter interaction can be used to induce quantum phase transition between normal and topological phases in two-dimensional topological insulators. We consider the case of a HgTe quantum well, in which band inversion occurs above a critical value of the well thickness, and demonstrate that coupling between electron states and the $E$ field from an off-resonant linearly polarized laser provides a powerful tool to control topological transitions, even for a thickness of the quantum well that is below the critical value. We also show that topological phase properties of the edge states, including their group velocity, can be tuned in a controllable way by changing the intensity of the laser field. These findings open up the possibility for new experimental means with which to investigate topological insulators and shed new light on topological-insulator-based technologies that are under active discussion.

cond-mat.mes-hall↗
arXiv2016

Self-consistent Purcell factor and spontaneous topological transition in hyperbolic metamaterials

In this work we develop a self-consistent approach for calculation of the Purcell factor and Lamb shift in highly dispersive hyperbolic metamaterial accounting for the effective dipole frequency shift. Also we theoretically predict the possibility of spontaneous topological transition, which occurs not due to the external change of the system parameters but only due to the Lamb shift.

physics.optics↗