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Sharp threshold-like transitions between two stable nuclear spin polarizations are observed in optically pumped individual InGaAs self-assembled quantum dots embedded in a Schottky diode when the bias applied to the diode is tuned. The…

We demonstrate room-temperature spin-polarized ultrafast ($\sim$10 ps) lasing in a highly optically excited GaAs microcavity. This microcavity is embedded with InGaAs multiple quantum wells in which the spin relaxation time is less than 10…

Mesoscale and Nanoscale Physics · Physics 2015-05-22 Feng-kuo Hsu , Wei Xie , Yi-Shan Lee , Sheng-Di Lin , Chih-Wei Lai

We present the manipulation of magnetic and electrical properties of (Ga,Mn)As by the adsorption of dye-molecules as a first step towards the realization of light-controlled magnetic-semiconductor/dye hybrid devices. A significant lowering…

Semiconductor structures using ferromagnetic semiconductors as spin injectors are promising systems for future spintronic devices. Here, we present combined photoluminescence (PL) and time-resolved magneto-optical experiments of a nominally…

Other Condensed Matter · Physics 2008-11-12 T. Korn , R. Schulz , S. Fehringer , U. Wurstbauer , D. Schuh , W. Wegscheider , M. W. Wu , C. Schüller

In the field of spin-controlled semiconductor lasers, massive effort has been focused upon materials with long spin relaxation times (~ns). In contrast, we demonstrate room-temperature spin-polarized ultrafast pulsed lasing in InGaAs…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Feng-kuo Hsu , Yi-Shan Lee , Sheng-Di Lin , Chih-Wei Lai

The photoluminescence polarizations of (In,Ga)As/GaAs quantum dots annealed at different temperatures are studied as a function of external magnetic field (Hanle curves). In these dependencies, remarkable resonant features appear due to…

We show by spatially and time-resolved photoluminescence that the application of an electric field transverse to the plane of an intrinsic GaAs (111) quantum well (QW) allows the transport of photogenerated electron spins polarized along…

Mesoscale and Nanoscale Physics · Physics 2019-03-13 A. Hernández-Mínguez , K. Biermann , R. Hey , P. V. Santos

Under suitable conditions, some twisted graphene multilayers and transition-metal dichalcogenides become Chern insulators, exhibiting the anomalous quantum Hall effect and orbital magnetization due to spontaneous valley polarization. We…

Mesoscale and Nanoscale Physics · Physics 2022-02-22 Sergey S. Pershoguba , Victor M. Yakovenko

We report on a picosecond-fast optical removal of spin polarization from a self-confined photo-carrier system at an undoped GaAs/AlGaAs interface possessing superior long-range and high-speed spin transport properties. We employed a…

Other Condensed Matter · Physics 2017-10-04 L. Nádvorník , M. Surýnek , K. Olejník , V. Novák , J. Wunderlich , F. Trojánek , T. Jungwirth , P. Němec

Magnetoresistance measurements on the magnetic semiconductor (In,Mn)Sb suggest that magnetic scattering in this material is dominated by isolated Mn$^{2+}$ ions located outside the ferromagnetically-ordered regions when the system is below…

Other Condensed Matter · Physics 2009-11-11 M. Csontos , T. Wojtowicz , X. Liu , M. Dobrowolska B. Jankó , J. K. Furdyna , G. Mihály

We study the optically induced spin polarization, spin dephasing and diffusion in several high-mobility two-dimensional electron systems, which are embedded in GaAs quantum wells grown on (110)-oriented substrates. The experimental…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 R. Voelkl , M. Schwemmer , M. Griesbeck , S. A. Tarasenko , D. Schuh , W. Wegscheider , C. Schueller , T. Korn

We consider magnetic properties of the planar structure consisting of a ferromagnetic metal, diluted magnetic semiconductor and the quantum well (by the example of the hybrid heterostructure Fe--Ga(Mn)As--InGaAs). In the framework of the…

Mesoscale and Nanoscale Physics · Physics 2015-05-18 E. Z. Meilikhov , R. M. Farzetdinova

We model the electron and hole spin dynamics in an undoped double quantum dot structure, considering the carrier tunneling between quantum dots. Taking into account also the presence of an in-plane or tilted magnetic field, we provide the…

Mesoscale and Nanoscale Physics · Physics 2018-01-15 Michał Gawełczyk , Paweł Machnikowski

We suggest a model of synthetic ferrimagnetic semiconductor structure based on GaAs-AlGaAs quantum well doped by two Mn delta-layers. The coupling between the delta-layers is mediated by extra holes, and can be switched between ferro- and…

Strongly Correlated Electrons · Physics 2020-03-19 N. V. Agrinskaya , A. M. Kalashnikova , V. I. Kozub

The sign, magnitude, and range of the exchange couplings between pairs of Mn ions is determined for (Ga,Mn)N and (Ga,Mn)N:Si with x < 3%. The samples have been grown by metalorganic vapor phase epitaxy and characterized by secondary-ion…

We present a detailed experimental and theoretical analysis of the optical orientation of electron spins in GaAs/AlAs quantum wells. Using time and polarization resolved photoluminescence excitation spectroscopy, the initial degree of…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 S. Pfalz , R. Winkler , T. Nowitzki , D. Reuter , A. D. Wieck , D. Haegele , M. Oestreich

The spin dynamics of a single Mn atom in a laser driven CdTe quantum dot is addressed theoretically. Recent experimental results\cite{Le-Gall_PRL_2009,Goryca_PRL_2009,Le-Gall_PRB_2010}show that it is possible to induce Mn spin polarization…

Mesoscale and Nanoscale Physics · Physics 2015-05-28 C. L. Cao , L. Besombes , J. Fernández-Rossier

In a bulk GaAs crystal, an unusual magnetoresistance effect, which takes place when a spin-polarized current flows through the sample, was detected. Under conditions of optical pumping of electron spins, an external magnetic field directed…

Mesoscale and Nanoscale Physics · Physics 2023-12-01 M. D. Ragoza , N. V. Kozyrev , S. V. Nekrasov , B. R. Namozov , Yu. G. Kusrayev , N. Bart , A. Ludwig , A. D. Wieck

The dynamic polarization of nuclear spins interacting with resident electrons under resonant excitation of trions is studied in a nominally undoped GaAs/(Al,Ga)As quantum well. Unlike in common time-resolved pump-probe techniques, we used a…

Mesoscale and Nanoscale Physics · Physics 2018-11-28 M. Kotur , F. Saeed , R. W. Mocek , V. L. Korenev , I. A. Akimov , A. S. Bhatti , D. R. Yakovlev , D. Suter , M. Bayer

We study the orbital and spin dynamics of charge carriers induced by non-overlapping linearly polarized light pulses in semiconductor quantum wells (QWs). It is shown that such an optical excitation with coherent pulses leads to a spin…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 A. V. Poshakinskiy , S. A. Tarasenko