Local control of spin flow in weak magnetic fields (2008)
Astakhov, G. V., Ossau, W., Molenkamp, L. W., Heinrich, J., Hofling, S., ...
We demonstrate that optical illumination strongly influences spin transport in n-type GaAs. Specifically, increasing the power density of optical spin pumping results in a significant expansion of...
Non-thermal photocoercivity effect in a ferromagnetic semiconductor (2008)
Astakhov, G. V., Hoffmann, H., Korenev, V. L., Kiessling, T., Schwittek, J., Schott, G. M., ...
We report a photoinduced change of the coercive field, i.e., a photocoercivity effect (PCE), under very low intensity illumination of a low-doped (Ga,Mn)As ferromagnetic semiconductor. We find a...
Time-resolved and continuous-wave optical spin pumping of semiconductor quantum wells (2008)
Astakhov, G. V., Glazov, M. M., Yakovlev, D. R., Zhukov, E. A., Ossau, W., Molenkamp, L. W., ...
Experimental and theoretical studies of all-optical spin pump and probe of resident electrons in CdTe/(Cd,Mg)Te semiconductor quantum wells are reported. A two-color Hanle-MOKE technique (based on...
Suppression of electron spin relaxation in Mn-doped GaAs (2007)
Astakhov, G. V., Dzhioev, R. I., Kavokin, K. V., Korenev, V. L., Lazarev, M. V., Tkachuk, M. N., ...
We report a surprisingly long spin relaxation time of electrons in Mn-doped p-GaAs. The spin relaxation time scales with the optical pumping and increases from 12 ns in the dark to 160 ns upon...
Bound magnetic polarons in the very dilute regime (2007)
Kusrayev, Yu. G., Kavokin, K. V., Astakhov, G. V., Ossau, W., Molenkamp, L. W.
We study bound magnetic polarons (BMP) in a very diluted magnetic semiconductor CdMnTe by means of site selective spectroscopy. In zero magnetic field we detect a broad and asymmetric band with a...
Exciton spin decay modified by strong electron-hole exchange interaction (2006)
Astakhov, G. V., Koudinov, A. V., Kavokin, K. V., Gagis, I. S., Kusrayev, Yu. G., Ossau, W., ...
We study exciton spin decay in the regime of strong electron-hole exchange interaction. In this regime the electron spin precession is restricted within a sector formed by the external magnetic field...
Hoffmann, H., Astakhov, G. V., Kiessling, T., Ossau, W., Karczewski, G., Wojtowicz, T., ...
We report on optical spin pumping of modulation electrons in CdTe-based quantum wells with low intrinsic electron density (by 10^10 cm^{-2}). Under continuous wave excitation, we reach a steady state...
Anomalous in-plane magneto-optical anisotropy of self-assembled quantum dots (2006)
Kiessling, T., Platonov, A. V., Astakhov, G. V., Slobodskyy, T., Mahapatra, S., Ossau, W., ...
We report on a complex nontrivial behavior of the optical anisotropy of quantum dots that is induced by a magnetic field in the plane of the sample. We find that the optical axis either rotates in...
Keller, D., Yakovlev, D. R., Astakhov, G. V., Ossau, W., Crooker, S. A., Slobodskyy, T., ...
The optical properties of two-dimensional electron gases in ZnSe/(Zn,Be)Se and ZnSe/(Zn,Be,Mg)Se modulation-doped quantum wells with electron densities up to 1.4x10^{12} cm^{-2} were studied by...
Quantum-dot-based optical polarization conversion (2005)
Astakhov, G. V., Kiessling, T., Platonov, A. V., Slobodskyy, T., Mahapatra, S., Ossau, W., ...
We report circular-to-linear and linear-to-circular conversion of optical polarization by semiconductor quantum dots. The polarization conversion occurs under continuous wave excitation in absence of...
Astakhov, G. V., Yakovlev, D. R., Rudenkov, V. V., Christianen, P. C. M., Barrick, T., Crooker, S. A., ...
The ground state of negatively charged excitons (trions) in high magnetic fields is shown to be a dark triplet state, confirming long-standing theoretical predictions. Photoluminescence (PL),...
Simple Estimation of X- Trion Binding Energy in Semiconductor Quantum Wells (2005)
Sergeev, R. A., Suris, R. A., Astakhov, G. V., Ossau, W., Yakovlev, D. R.
A simple illustrative wave function with only three variational parameters is suggested to calculate the binding energy of negatively charged excitons (X-) as a function of quantum well width. The...
Magnetic Field Effects on Carriers Capture to Quantum Dots (2002)
Astakhov, G. V., Kochereshko, V. P., Evtikhiev, V. P., Tokranov, V. E., Kudryashov, I. V.
An effect of carrier redistribution between different size quantum dots (QD) in a self-ordered InAs/GaAs QD structures has been studied by magneto-luminescence (PL) at helium temperatures.
Charged Excitons in ZnSe-Based QWs (2002)
Yakovlev, D. R., Astakhov, G. V., Kochereshko, V. P., Keller, A., Ossau, W.
We report on magneto-optical studies of ZnSe/(Zn,Mg)(S,Se) and ZnSe/(Zn,Be,Mg)Se quantum wells with n type and p type modulation doping. Negatively and positively charged excitons related to the...
Spectroscopy of Negatively Charged Excitons Interacting With 2DEG in CdTe/(Cd,Mg)Te QWs (2002)
Astakhov, G. V., Kochereshko, V. P., Yakovlev, D. R., Suris, R. A., Ossau, W.
We report on experimental observation of a combined exciton-electron processes in which an incident photon creates a trion (negatively charged exciton-electron complex) and promotes an inter-Landau...
Binding energy of charged excitons in ZnSe-based quantum wells (2002)
Astakhov, G. V., Yakovlev, D. R., Kochereshko, V. P., Ossau, W., Faschinger, W., Puls, J., ...
Optical Method for Determination of Carrier Density in Modulation Doped Quantum Wells (2001)
Astakhov, G. V., Kochereshko, V. P., Yakovlev, D. R., Ossau, W., Nurnberger, J., Faschinger, W., ...
An optical method is suggested to determine the concentration of two-dimensional electrons in modulation-doped quantum wells at low and moderate electron densities between 10^{9} and 2x10^{11}...
Binding Energy of Charged Excitons in ZnSe-based Quantum Wells (2001)
Astakhov, G. V., Yakovlev, D. R., Kochereshko, V. P., Ossau, W., Puls, J., Henneberger, F., ...
Excitons and charged excitons (trions) are investigated in ZnSe-based quantum well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of magneto-optical spectroscopy. Binding energies...
Astakhov, G. V., Kosobukin, V. A., Kochereshko, V. P., Yakovlev, D. R., Ossau, W., Landwehr, G., ...
An approach is proposed to determine parameters of homogeneous and inhomogeneous broadening for reflection lines of quasi-two-dimensional excitons in semiconductor quantum well structures. A...