arXiv subjects

M. M. Glazov

Publications and source records attributed to M. M. Glazov.

At least 163 records · Page 9Linked to original sources

arXiv2007

Spin coherence of a two-dimensional electron gas induced by resonant excitation of trions and excitons in CdTe/(Cd,Mg)Te quantum wells

The mechanisms for generation of long-lived spin coherence in a two-dimensional electron gas (2DEG) have been studied experimentally by means of a picosecond pump-probe Kerr rotation technique. CdTe/(Cd,Mg)Te quantum wells with a diluted 2DEG were investigated. The strong Coulomb interaction between electrons and holes, which results in large binding energies of neutral excitons and negatively charged excitons (trions), allows one to address selectively the exciton or trion states by resonant optical excitation. Different scenarios of spin coherence generation were analyzed theoretically, among them the direct trion photocreation, the formation of trions from photogenerated excitons and the electron-exciton exchange scattering. Good agreement between experiment and theory is found.

cond-mat.mes-hall↗

arXiv2007

Light-matter interaction in doped microcavities

We discuss theoretically the light-matter coupling in a microcavity containing a quantum well with a two-dimensional electron gas. The high density limit where the bound exciton states are absent is considered. The matrix element of interband optical absorbtion demonstrates the Mahan singularity due to strong Coulomb effect between the electrons and a photocreated hole. We extend the non-local dielectric response theory to calculate the quantum well reflection and transmission coefficients, as well as the microcavity transmission spectra. The new eigenmodes of the system are discussed. Their implications for the steady state and time resolved spectroscopy experiments are analyzed.

cond-mat.mes-hall↗

arXiv2007

Effect of structure anisotropy on low temperature spin dynamics in quantum wells

Spin dynamics of two-dimensional electron gas confined in an asymmetrical quantum well is studied theoretically in the regime where the scattering frequency is comparable with the spin precession frequency due to the conduction band spin splitting. The spin polarization is shown to demonstrate quantum beats. If the spin splitting is determined by both bulk and structural asymmetry mechanisms the beats are damped at zero temperature even in the absence of a scattering. We calculate the decay of spin beats due to the thermal broadening of the electron distribution function and electron scattering. The magnetic field applied along the structure growth axis is shown to increase the frequency of the beats and shift system towards the collision dominated regime.

cond-mat.mes-hall↗

arXiv2007

Bose glass and superfuid phases of cavity polaritons

We report the calculation of cavity exciton-polariton phase diagram which takes into account the presence of realistic structural disorder. Polaritons are modelled as weakly interacting two-dimensional bosons. We show that with increasing density polaritons first undergo a quasi-phase transition towards a Bose glass: the condensate is localized in at least one minimum of the disorder potential, depending on the value of the chemical potential of the polariton system. A further increase of the density leads to a percolation process of the polariton fluid which gives rise to a Kosterlitz-Thouless phase transition towards superfluidity. The spatial representation of the condensate wavefunction as well as the spectrum of elementary excitations are obtained from the solution of the Gross-Pitaevskii equation for all the phases.

cond-mat.mtrl-sci↗

arXiv2006

Fine structure of exciton excited levels in a quantum dot with a magnetic ion

The fine structure of excited excitonic states in a quantum dot with an embedded magnetic ion is studied theoretically and experimentally. The developed theory takes into account the Coulomb interaction between charged carriers, the anisotropic long-range electron-hole exchange interaction in the zero-dimensional exciton, and the exchange interaction of the electron and the hole with the $d$-electrons of a Mn ion inserted inside the dot. Depending on the relation between the quantum dot anisotropy and the exciton-Mn coupling the photoluminescence excitation spectrum has a qualitatively different behavior. It provides a deep insight into the spin structure of the excited excitonic states.

cond-mat.mes-hall↗

arXiv2006

Enhanced spin relaxation time due to electron-electron scattering in semiconductors

We present a detailed experimental and theoretical analysis of the spin dynamics of two-dimensional electron gases (2DEGs) in a series of n-doped GaAs/AlGaAs quantum wells. Picosecond-resolution polarized pump-probe reflection techniques were applied in order to study in detail the temperature-, concentration- and quantum-well-width- dependencies of the spin relaxation rate of a small photoexcited electron population. A rapid enhancement of the spin life-time with temperature up to a maximum near the Fermi temperature of the 2DEG was demonstrated experimentally. These observations are consistent with the D'yakonov-Perel' spin relaxation mechanism controlled by electron-electron collisions. The experimental results and theoretical predictions for the spin relaxation times are in good quantitative agreement.

cond-mat.mes-hall↗

arXiv2006

Nonlinear effects in spin relaxation of cavity polaritons

We present the general kinetic formalism for the description of spin and energy relaxation of the cavity polaritons in the framework of the Born-Markov approximation. All essential mechanisms of polaritons redistribution in reciprocal space together with final state bosonic stimulation are taken into account, from our point of view. The developed theory is applied to describe our experimental results on the polarization dynamics obtained in the polariton parametric amplifier geometry (pumping at so-called magic angle). We have experimentally confirmed that the anisotropy of the polariton-polariton interaction is responsible for the build up of the cross-linear polarisation of the signal. The long-living linear polarization is observed at zero detuning. Under elliptical pumping, we have directly measured in the time domain and modelled the effect of self-induced Larmor precession.

cond-mat.mes-hall↗

arXiv2006

Non-Markovian spin relaxation in two-dimensional electron gas

We analyze by Monte-Carlo simulations and analytically spin dynamics of two-dimensional electron gas (2DEG) interacting with short-range scatterers in nonquantizing magnetic fields. It is shown that the spin dynamics is non-Markovian with the exponential spin relaxation followed by the oscillating tail due to the electrons residing on the closed trajectories. The tail relaxes on a long time scale due to an additional smooth random potential and inelastic processes. The developed analytical theory and Monte-Carlo simulations are in the quantitative agreement with each other.

cond-mat.mes-hall↗

arXiv2006

Optical Anisotropy and Pinning of the Linear Polarization of Light in Semiconductor Microcavities

We report a strong experimental evidence of the optical anisotropy in a CdTe-based microcavity: the polarization of light is pinned to one of the crystallographic axes independently on the polarization of the excitation. The polarization degree depends strongly on the excitation power, reaching almost 100 % in the stimulated regime. The relaxation time of the polarization is about 1 ns. We argue that all this is an effect of a splitting of the polariton doublet at k=0. We consider different sources for the splitting and conclude that the most likely one is optical birefringence in the mirrors and/or the cavity.

cond-mat.mtrl-sci↗

arXiv2006

Interplay of Rashba and Dresselhaus spin splittings in 2D weak localization

The effects of structural (Rashba) and bulk (Dresselhaus) spin-orbit interaction terms on the low-field magnetoresistance are investigated in high-quality two dimensional systems. The weak localization theory accounting for both of these terms valid in the whole range of magnetic fields is proposed. The suppresion of antilocalization correction as Rashba and Dresselhaus terms strengths approach each other is demonstrated. The effect of cubic in the wavevector spin-splitting term is analyzed.

cond-mat.mes-hall↗

arXiv2005

Statistics of excitons in quantum dots and the resulting microcavity emission spectra

A theoretical investigation is presented of the statistics of excitons in quantum dots (QDs) of different sizes. A formalism is developed to build the exciton creation operator in a dot from the single exciton wavefunction and it is shown how this operator evolves from purely fermionic, in case of a small QD, to purely bosonic, in case of large QDs. Nonlinear optical emission spectra of semiconductor microcavities containing single QDs are found to exhibit a peculiar multiplet structure which reduces to Mollow triplet and Rabi doublet in fermionic and bosonic limits, respectively.

cond-mat.mes-hall↗

arXiv2005

Non-exponential spin relaxation in magnetic field in quantum wells with random spin-orbit coupling

We investigate the spin dynamics of electrons in quantum wells where the Rashba type of spin-orbit coupling is present in the form of random nanosize domains. We study the effect of magnetic field on the spin relaxation in these systems and show that the spatial randomness of spin-orbit coupling limits the minimum relaxation rate and leads to a Gaussian time-decay of spin polarization due to memory effects. In this case the relaxation becomes faster with increase of the magnetic field in contrast to the well known magnetic field suppression of spin relaxation.

cond-mat.mes-hall↗

arXiv2005

Fine structure of excited excitonic states in quantum disks

We report on a theoretical study of the fine structure of excited excitonic levels in semiconductor quantum disks. A particular attention is paid to the effect of electron-hole long-range exchange interaction. We demonstrate that, even in the axisymmetric quantum disks, the exciton P-shell is split into three sublevels. The analytical results are obtained in the limiting cases of strong and weak confinement. A possibility of exciton spin relaxation due to the resonant LO-phonon-assisted coupling between the P and S shells is discussed.

cond-mat.mes-hall↗

arXiv2004

Suppression of spin beats in magneto-oscillation phenomena in two-dimensional electron gas

Theory of magneto-oscillation phenomena has been developed for two-dimensional electron systems with linear-in-k spin splitting. Both Dresselhaus and Rashba contributions are taken into account. It has been shown that the pattern of the magneto-oscillations depends drastically on the ratio between the above terms. The presence of only one type of the k-linear terms gives rise to the beats, i.e. two close harmonics corresponding to the spin-split subbands. However, if the strengths of both contributions are comparable, the third (central) harmonics appears in the spectrum of the magneto-oscillations. For equal strengths of the contributions, only the central harmonic survives, and the oscillations occur at a single frequency, although the k-linear terms remain in the Hamiltonian. Such suppression of the spin beats is studied in detail by the example of the Shubnikov-de Haas effect.

cond-mat.mes-hall↗

arXiv2004

Spin-dependent resonant tunneling in symmetrical double-barrier structure

A theory of resonant spin-dependent tunneling has been developed for symmetrical double-barrier structures grown of non-centrosymmetrical semiconductors. The dependence of the tunneling transparency on the spin orientation and the wave vector of electrons leads to (i) spin polarization of the transmitted carriers in an in-plane electric field, (ii) generation of an in-plane electric current under tunneling of spin-polarized carriers. These effects originated from spin-orbit coupling-induced splitting of the resonant level have been considered for double-barrier tunneling structures.

cond-mat.mes-hall↗

arXiv2004

Cavity polaritons: Classical behaviour of a quantum parametric oscillator

We address theoretically the optical parametric oscillator based on semiconductor cavity exciton-polaritons under a pulsed excitation. A "hyperspin" formalism is developed which allows, in the case of large number of polaritons, to reduce quantum dynamics of the parametric oscillator wavefunction to the Liouville equation for the classical probability distribution. Implications for the statistics of polariton ensembles are analyzed.

cond-mat.mes-hall↗

arXiv2004

Magnetic field effects on spin relaxation in heterostructures

Effect of magnetic field on electron spin relaxation in quantum wells is studied theoretically. We have shown that Larmor effect and cyclotron motion of carriers can either jointly suppress D'yakonov-Perel' spin relaxation or compensate each other. The spin relaxation rates tensor is derived for any given direction of the external field and arbitrary ratio of bulk and structural contributions to spin splitting. Our results are applied to the experiments on electron spin resonance in SiGe heterostructures, and enable us to extract spin splitting value for such quantum wells.

cond-mat.mes-hall↗

arXiv2004

Spin injection and detection by resonant tunneling structure

A theory of spin-dependent electron transmission through resonant tunneling diode (RTD) grown of non-centrosymmetrical semiconductor compounds has been presented. It has been shown that RTD can be employed for injection and detection of spin-polarized carriers: (i) electric current flow in the interface plane leads to spin polarization of the transmitted carriers, (ii) transmission of the spin-polarized carriers through the RTD is accompanied by generation of an in-plane electric current. The microscopic origin of the effects is the spin-orbit coupling-induced splitting of the resonant level.

cond-mat.mes-hall↗