arXiv subjects

E. L. Ivchenko

Publications and source records attributed to E. L. Ivchenko.

At least 19 recordsLinked to original sources

arXiv2026

Long-range exchange interaction controls the fine structure of excited trion states in semiconductor quantum dots

We develop a microscopic theory of the long-range electron-hole exchange interaction in charged excitons (trions) confined in semiconductor quantum dots. While the ground-state singlet trion remains degenerate in the spin component of unpaired charge carrier by time-reversal symmetry, excited trion states exhibit a rich fine structure resulting from the interplay of electron-electron and electron-hole exchange interactions. We derive the effective long-range exchange Hamiltonian for both the spin-$3/2$ heavy-hole and a simple spin-$1/2$ valence band models. The long-range exchange interaction mixes singlet and triplet trion configurations, giving rise to anisotropic fine-structure splittings and related polarization-dependent optical spectra determined by the quantum-dot shape. Analytical expressions are obtained for the long-range exchange parameters. The developed theory establishes a unified microscopic description of the fine structure of excited trions in semiconductor quantum dots and provides a framework for interpreting polarization-resolved optical spectroscopy of charged excitonic complexes.

cond-mat.mes-hall↗

arXiv2026

Random fine structure and polarized luminescence of triplet excitons in semiconductor nanocrystals

We present a theory of polarized photoluminescence of triplet excitons in semiconductor nanocrystal ensembles with the random fine structure contributed by the electron-hole exchange and carrier-nuclear hyperfine interactions. The interaction parameters are assumed to be normally and isotropically distributed. In particular, the exchange interaction is described by the Gaussian orthogonal ensemble of random matrices. The intensity of luminescence as well as the optical orientation and alignment are calculated as functions of the fine structure splitting parameters and the exciton lifetime. We have also analyzed the suppression of optical alignment and enhancement of optical orientation in an external longitudinal magnetic field.

cond-mat.mes-hall↗

arXiv2025

Ultimate photon entanglement in biexciton cascade

The polarization entanglement of photons emitted by semiconductor quantum dots is unavoidably limited by the spin fluctuations of the host lattice nuclei. To overcome this limitation, we develop a theory of entangled photon pair generation by a symmetric colloidal quantum dot mediated by a triplet exciton. We derive general analytical expressions for the concurrence as a function of the hyperfine interaction strength and show that it is intrinsically higher than that in conventional doublet-exciton systems such as self-assembled quantum dots. The concurrence sensitively depends on the shape anisotropy and the strain applied to a nanocrystal. In particular, we uncover a possibility of completely suppressing the detrimental effect of the hyperfine interaction due to the interplay between nanocrystal anisotropy and electron-hole exchange interaction. We argue that this represents the ultimate limit for the generation of entangled photon pairs by semiconductor quantum dots.

cond-mat.mes-hall↗

arXiv2025

Electron and hole $g$ factors in semiconductors and nanostructures (Review)

We present a review of experimental and theoretical studies of the spin response of charge carriers to an external magnetic field in bulk semiconductors and semiconductor nanostructures. The linear response is quantitatively characterized by the magnitude of the electron or hole g factor. Various experimental methods for measuring the electron g factor are considered, beginning with historical works and including modern research. A detailed analysis of theoretical methods for calculating the electron and hole g factors in bulk semiconductors and nanostructures of various shapes also includes fundamental work from previous years and the present time.

cond-mat.mtrl-sci↗

arXiv2025

Trembling motion of electrons driven by Larmor spin precession

We show that the initialization of an ensemble of electrons in the same spin state in strained n-InGaAs subject to a perpendicular magnetic field triggers an AC electric current at GHz frequencies. The AC current emerges in the absence of any driving force and survives until the coherent precession of the electron spins is lost. The current amplitude increases linearly with both the spin-orbit coupling strength and the external magnetic field. The generation mechanism of the observed oscillatory charge motion can be fruitfully described in terms of the periodic trembling motion of spin-polarized electrons, which is a solid-state analog to the Zitterbewegung of free Dirac electrons. Our results demonstrate that the hidden consequence of relativistic quantum mechanics is realized and can be studied in a rather simple solid-state system at moderate temperatures. Furthermore, the large amplitude of the AC current at high magnetic fields enables ultra-fast spin sensitive electric read-out in solids.

cond-mat.mes-hall↗

arXiv2025

Intraband circular photogalvanic effect in Weyl semimetals

We apply the semiclassical theory including the Berry curvature dipole, side jumps and skew scattering for a quantitative description of the circular photogalvanic effect (CPGE) in Weyl semimetals at intraband absorption. In contrast to gapped systems where they completely exhaust all contributions to the CPGE current, all previously known semiclassical mechanisms give a result different from that obtained using a complete quantum-mechanical approach. We show that this difference in the existing quasiclassical and full quantum-mechanical approaches persists at all spatial ranges of the disorder potential. Apparently, the implementation of another microscopic mechanism into the quasiclassical description of the CPGE is required.

cond-mat.mes-hall↗

arXiv2025

Nonreciprocal magnetic-field-induced second harmonic generation of exciton polaritons in ZnSe

We report on the optical second harmonic generation (SHG) on the 1S exciton-polariton resonance in bulk ZnSe that is subject to an external magnetic field applied perpendicular to the light wave vector $\mathbf k$ (Voigt geometry). For the symmetry allowed geometry with the $\mathbf{k}\parallel[111]$ crystal axes, the nonreciprocal dependence of the SHG intensity on the magnetic field direction is found. It is explained by an interference of the crystallographic and magnetic-field-induced SHG signals. Relative phases of these signals are evaluated from the rotational anisotropy diagrams. Phenomenological and microscopic models of the effect are developed. To the best of our knowledge, this is the first experimental observation of the nonreciprocal SHG in semiconductor crystals, and the first one for exciton-polaritons.

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arXiv2025

Photocurrents induced by k-linear terms in semiconductors and semimetals

We develop a six-band $\mathbf{k} \cdot \mathbf{p}$ model to describe the electronic structure and optical response of chiral multifold semimetals, such as RhSi. By means of invariants method we construct the effective Hamiltonian describing the states near the $\Gamma$-point of the Brillouin zone where the spin-orbit coupling and $\mathbf{k}$-linear Rashba terms, which are crucial for circular photogalvanic effect, are taken into account. The model is parameterized using tight-binding calculations. We compute the interband absorption spectrum, showing a linear-in-frequency dependence at low energies and a resonant feature near the spin-orbit splitting energy. Furthermore, we calculate the circular photogalvanic effect. In agreement with previous works the current generation rate at low frequencies exhibits a quantized low-frequency response, governed by the universal value $|\mathcal{C}| = 4$ for the effective topological charge. Our results provide an analytical framework for understanding the role of Rashba coupling and topology in the optoelectronic properties of multifold chiral semimetals.

cond-mat.mes-hall↗

arXiv2024

Hanle effect in current induced spin orientation

Electrical spin orientation is the generation of electron spin proportional to the electric current. This phenomenon is allowed by symmetry in gyrotropic systems, e.g. in inversion-asymmetric structures with Rashba spin-orbit splitting. Here we develop a theory of electrical spin orientation for magnetic two-dimensional heterostructures. Spin-orbit coupled graphene and semiconductor heterostructures proximitized by ferromagnets are considered. The analytical theory is based on the Boltzmann kinetic equation for a spin-dependent distribution function and collision integral. We show that the induced spin demonstrates the Hanle effect: a direction of the spin depends on the out-of-plane magnetization. Importantly, the Hanle effect is extremely sensitive to the details of electron elastic scattering. In semiconductor heterostructures, the effect of magnetization is present for scattering by long-range disorder and absent for short-range scattering. In spin-orbit-coupled graphene, the Hanle effect occurs at any scattering potential, but the direction of the spin strongly changes with variation of the disorder type. The theory also describes the effect of valley-Zeeman splitting on the electrical spin orientation in graphene, where the spin experiences opposite Hanle effects in two valleys.

cond-mat.mes-hall↗

arXiv2024

Influence of Coulomb interaction on interband photogalvanic effect in semiconductors

The ballistic and shift contributions to the interband linear photogalvanic effect are calculated in the same band structure model of a noncentrosymmetric semiconductor. The calculation uses a two-band generalized Dirac effective Hamiltonian with the off-diagonal components containing $\mathbf{ k}$-dependent terms of the first and second order. The developed theory takes into account the Coulomb interaction between the photoexited electron and hole. It is shown that in typical semiconductors the ballistic photocurrent $j^{({\rm bal})}$ significantly exceeds the shift current $j^{({\rm sh})}$: the ratio $j^{({\rm sh})}/j^{({\rm bal})}$ has the order of $a_B/ \ell$, where $a_B$ is the Bohr radius and $\ell$ is the mean free path of photocarriers due to their quasi-momentum scattering.

cond-mat.mes-hall↗

arXiv2024

Interplay between hyperfine and anisotropic exchange interactions in exciton luminescence of quantum dots

The optical orientation and alignment of excitons in semiconductor indirect gap quantum dots have been studied theoretically. A special regime is analyzed in which the energy of the hyperfine interaction of an electron with lattice nuclei is small compared to the exchange splitting between bright and dark excitonic levels, but is comparable to the anisotropic exchange splitting of the radiative doublet. The dependencies of degrees of circular and linear polarization on the external magnetic field under resonant excitation of excitons by polarized light are calculated.

cond-mat.mes-hall↗

arXiv2024

Theory of acoustic-phonon involved exciton spin flip in perovskite semiconductors

We present a theory of the acoustic phonon assisted spin-flip Raman scattering (SFRS), or resonant photoluminescence with the spin flip of a photoexcited exciton localized in a bulk cubic-phase perovskite semiconductor. We consider the spin-flip transitions between the ground-state exciton spin sublevels in external magnetic field B and discuss the variation of their probability rate and polarization selection rules with the increase of B. The transitions are treated as two-quantum processes with the virtual to and fro transfer of the electron in the electron-hole pair between the bottom and first excited conduction bands. The transfer occurs due to both the electron-hole exchange interaction and the electron-phonon interaction. The theoretical results allow one to distinguish the phonon assisted Raman scattering from (a) the resonant Raman scattering with the combined spin flip of the localized resident electron and hole and (b) the biexciton-mediated SFRS analyzed previously.

cond-mat.mtrl-sci↗

arXiv2023

Tailoring the electron and hole Landé factors in lead halide perovskite nanocrystals by quantum confinement and halide exchange

The tunability of the optical properties of lead halide perovskite nanocrystals makes them highly appealing for applications. Both, halide anion exchange and quantum confinement pave the way for tailoring their band gap energy. For spintronics applications, the Landé g-factors of electrons and hole are of great importance. By means of the empirical tight-binding and $\textbf{k}\cdot\textbf{p}$ methods, we calculate them for nanocrystals of the class of all-inorganic lead halide perovskites CsPb$X_3$ ($X = \text{I},\,\text{Br},\,\text{Cl}$). The hole g-factor as function of the band gap follows the universal dependence found for bulk perovskites, while for the electrons a considerable modification is predicted. Based on the $\textbf{k}\cdot\textbf{p}$ analysis we conclude that this difference arises from the interaction of the bottom conduction band with the spin-orbit split electron states. The model predictions are confirmed by experimental data for the electron and hole g-factors in CsPbI3 nanocrystals placed in a glass matrix, measured by time-resolved Faraday ellipticity in a magnetic field at cryogenic temperatures.

cond-mat.mes-hall↗

arXiv2023

Theory of polarized photoluminescence of indirect band gap excitons in type-I quantum dots

In this work, we theoretically investigate the optical orientation and alignment of excitons in quantum dots with weak electron-hole exchange interaction and long exciton radiative lifetimes. This particular regime is realized in semiconductor heterosystems where excitons are indirect in the $\boldsymbol r$ or $\boldsymbol k$ space. The main role in the fine structure of excitonic levels in these systems is played by the hyperfine interaction of the electron in the confined exciton and fluctuations of the Overhauser field. Along with it, the effects of nonradiative recombination and exchange interaction are considered. We start with the model of vanishing exchange interaction and nonradiative exciton recombination and then include them into consideration in addition to the strong Overhauser field. In the nanoobjects under study, the polarization properties of the resonant photoluminescence are shown to vary with the external magnetic filed in completely different way as compared with the behaviour of the conventional quantum dot structures.

cond-mat.mes-hall↗

arXiv2023

Electrical Magnetochiral current in Tellurium

We have studied theoretically the effect of Electrical Magneto-Chiral Anisotropy (eMChA) in $p$-type tellurium crystals. It is shown that the terms $k_i B_j$ in the hole Hamiltonian, linear both in the wave vector ${\mathbf k}$ and the magnetic field ${\mathbf B}$, do not lead to the eMChA and one needs to include the higher-order terms like $k_i^3 B_j$. Two microscopic mechanisms of the effect are considered. In the first one only elastic scattering of holes by impurities or imperfections are taken into consideration only. In the second mechanism, besides the elastic scattering processes the hole gas heating and its energy relaxation are taken into account. It is demonstrated that he both contributions to the magneto-induced rectification are comparable in magnitude. The calculation is performed by using two independent approaches, namely, in the time relaxation approximation and in the limit of of small chiral band parameter $\beta$. A bridge is thrown between the eMChA and magneto-induced photogalvanic effects.

cond-mat.mes-hall↗

arXiv2022

Theory of resonant Raman scattering due to spin-flips of resident charge carries and excitons in perovskite semiconductors

We have developed a theory of Raman scattering with single and double spin flips of localized resident electrons and holes as well as nonequilibrium localized excitons in semiconductor perovskite crystals under optical excitation in the resonant exciton region. Scattering mechanisms involving localized excitons, biexcitons and exciton polaritons as intermediate states has been examined, the spin-flip Raman scattering by polaritons being a novel mechanism. The derived equations are presented in the invariant form allowing one for the analysis of the dependence of scattering efficiency on the polarization of the initial and scattered light and on the orientation of the external magnetic field.

cond-mat.mtrl-sci↗

arXiv2022

Optical transitions, exciton radiative decay, and valley coherence in lead chalcogenide quantum dots

We propose the concept of valley coherence and superradiance in the reciprocal space and show that it leads to an $N$-fold decrease of the bright exciton radiative lifetime in quantum dots (QDs) of an $N$-valley semiconductor. Next we explain why, despite this, the exciton radiative lifetimes in PbX (X = S, Se, Te) QDs, measured from the photoluminescence decay, are in the microsecond range. We also address peculiarities of the light-matter interaction in nanostructures made of narrow-gap materials with strong inter-band coupling.

cond-mat.mes-hall↗

arXiv2021

The Landé factors of electrons and holes in lead halide perovskites: universal dependence on the band gap

The Landé or $g$-factors of charge carriers are decisive for the spin-dependent phenomena in solids and provide also information about the underlying electronic band structure. We present a comprehensive set of experimental data for values and anisotropies of the electron and hole Landé factors in hybrid organic-inorganic (MAPbI$_3$, MAPb(Br$_{0.5}$Cl$_{0.5}$)$_3$, MAPb(Br$_{0.05}$Cl$_{0.95}$)$_3$, FAPbBr$_3$, FA$_{0.9}$Cs$_{0.1}$PbI$_{2.8}$Br$_{0.2}$) and all-inorganic (CsPbBr$_3$) lead halide perovskites, determined by pump-probe Kerr rotation and spin-flip Raman scattering in magnetic fields up to 10~T at cryogenic temperatures. Further, we use first-principles DFT calculations in combination with tight-binding and $\mathbf k \cdot \mathbf p$ approaches to calculate microscopically the Landé factors. The results demonstrate their universal dependence on the band gap energy across the different perovskite material classes, which can be summarized in a universal semi-phenomenological expression, in good agreement with experiment.

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