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1
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Magnetic Polaron Formation in Semimagnetic Semiconductor Heterostructures

100%
Yakovlev D.
Acta Physica Polonica A
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1996
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vol. 90
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issue 4
703-714
EN
We present a survey of experimental and theoretical studies of exciton magnetic polarons in semimagnetic semiconductor epilayers, quantum wells and superlattices. The emphasis is on dynamical aspects of magnetic polaron formation in systems of different dimensionality.
2
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Luminescent Probe for Highly Energetic Collisions in Mixtures of Complex Molecules with Acceptors of Vibrational and Triplet Energy

51%
Zalesskaya G., Yakovlev D., Sambor E., Baranovsky D.
|
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vol. 95
|
issue 6
897-910
EN
Pressure dependences of intensities and decay rates of time-resolved luminescence of acetophenone, benzophenone, anthraquinone were used to obtain the efficiencies of vibrational and triplet-triplet energy transfer. It was shown that vibrational relaxation of the chosen molecules can be interpreted in terms of two consecutive processes: rapid collisional relaxation of molecules from initially prepared states to a vibrational distribution at T_{vib} by vibration-vibration process and relaxation of this vibrational distribution to the thermal one (vibration-translation process). At relatively small internal energy < 10000 cm^{-1}, the collisional efficiencies of the vibration-vibration process in mixtures with polyatomic bath gases had values typical of processes with a supercollision contribution. Molecules relaxed from the upper vibrational level to the vibrational distribution after several collisions (2-3). The average energies transferred per collision are well correlated with predictions of the simple ergodic theory of collisional energy transfer. The majority of the collisions took part only in vibration-translation energy transfer of relatively small energies. The efficiencies of triplet-triplet energy transfer were analyzed for acetophenone, benzophenone and anthraquinone as donors and biacetyl-acceptor in a gas phase when energy of about 20000 cm^{-1} was transferred. It permitted us to elucidate the common features of highly energetic collisions. It was shown that the efficiencies are much lower than the gas kinetic ones and depended on the vibrational energy and temperature. It was discussed how to enhance triplet-triplet efficiencies due to vibrational excitation of a donor molecule.
3
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Effect of Magnetic Polaron Formation on the Exciton Mobility Edge in Cd_{1-x}Mn_{x}Te

45%
Mackh G., Yakovlev D., Ossau W., Waag A., Landwehr G.
Acta Physica Polonica A
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1995
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vol. 87
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issue 1
265-268
EN
We study the exciton localization in the semimagnetic semiconductor Cd_{1-x}Mn_{x}Te by selective excitation of the exciton photoluminescence. We show that the energy position of the effective mobility edge for excitons is subject to the competition between nonmagnetic and magnetic localization due to the magnetic polaron formation. External magnetic fields affect this competition by suppressing the polaron formation, which shifts the mobility edge.
4
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Effect of Spin-Glass Phase Formation on Exciton Magnetic Polaron in (Cd,Mn)Te

39%
Chudnovskiy A. L., Rosenow B., Oppermann R., Yakovlev D., Zehnder U., Ossau W.
Acta Physica Polonica A
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1996
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vol. 90
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issue 4
755-758
EN
The influence of the spin-glass phase formation of the (Cd,Mn)Te semimagnetic layers on properties of the exciton magnetic polaron were investigated both theoretically and experimentally. The theoretical model offers a consistent description of the temperature dependence of the exciton magnetic polaron energy in the vicinity of spin-glass transition and shows good agreement with the experimental data.
5
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Optically Detected Magnetic Resonance of Excess Electrons in CdTe/(Cd,Mg)Te Quantum Wells

39%
Hu C., Ossau W., Yakovlev D., König B., Wojtowicz T., Karczewski G., Kossut J.
Acta Physica Polonica A
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1998
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vol. 94
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issue 2
351-354
EN
The spin resonance of excess electrons is observed with the detection either on the neutral or the negatively charged exciton X^{-} emission in type I CdTe/(Cd,Mg)Te quantum wells with excess electrons of low density. It is found that the electron spin-dependent and electron spin-conserving formation and recombination of X^{-} make the optical detection of the spin resonance of excess electrons feasible. For the first time, optically detected magnetic resonance is used to study fast optical transition processes in the nanosecond timescale where the microwave-induced magnetic transition rate is much lower than the optical transition rate.
6
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Optical Anisotropy of ZnSe/BeTe Superlattices Probed by Excitonic Spectroscopy

33%
Platonov A., Kochereshko V., Ivchenko E., Yakovlev D., Ossau W., Fischer F., Waag A., Landwehr G.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
479-482
EN
Photoluminescence spectra of type-II ZnSe/BeTe superlattices were studied. A linear polarised photoluminescence has been found in the spectral range of spatially indirect exciton transitions. This observation is interpreted in a model of optical anisotropy of heterostructures with no-common atom at interfaces.
7
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Exciton Exchange between Nearly-Free and Acceptor-Bound States of a Positive Trion Assisted by Cyclotron Excitation

33%
Jadczak J., Bryja L., Wójs A., Bartsch G., Yakovlev D., Bayer M., Plochocka P., Potemski M., Reuter D., Wieck A.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
600-601
EN
In magneto-photoluminescence spectra of a two-dimensional hole gas in a GaAs quantum well we observe coupling of two different radiative states. The pair of coupled states are an acceptor-bound trion AX^{+} and an essentially free (only weakly localized by a shallow lateral potential) trion X^{+}, brought into resonance by an additional cyclotron excitation controlled by the magnetic field. The coupling mechanism is the exciton transfer, and the optical signature is a clear anticrossing of the emission lines of an X^{+} and a cyclotron replica of the AX^{+}.
8
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Model Study of Inhomogeneous Line Broadening in Excitonic Spectra of Quantum Wells

33%
Astakhov G., Kochereshko V., Kosobukin V., Yakovlev D., Wojtowicz T., Karczewski G., Kossut J., Ossau W., Landwehr G.
Acta Physica Polonica A
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1998
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vol. 94
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issue 2
235-239
EN
An approach is proposed to estimate separately parameters of homogeneous and inhomogeneous broadenings from an optical reflection line of a quasi-2D exciton. A phenomenological model is proposed to take into account statistically an inhomogeneous broadening of the exciton resonant spectra. The concept is applied to study a modulation-doped heterostructures with a single quantum well CdTe/CdMgTe. From exciton reflection lines taken in a magnetic field the temperature-dependent homogeneous and inhomogeneous broadening parameters as well as the exciton radiative decay rate are measured.
9
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Electron Spins in Self-Assembled (In,Ga)As/GaAs Quantum Dots Studied by Pump-Probe Faraday Rotation

27%
Greilich A., Yugova I., Oulton R., Zhukov E., Yakovlev D., Bayer M., Shabaev A., Efros A., Stavarache V., Reuter D., Wieck A.
Acta Physica Polonica A
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2006
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vol. 110
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issue 3
287-293
EN
Static and dynamic properties of electron spins in self-assembled (In,Ga)As/GaAs quantum dots which contain on average a single electron per dot were studied by pump-probe Faraday rotation. Examples given here are the g-factor tensor components as well as the dephasing time T*_2 within a dot ensemble.
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