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We have studied the physical processes responsible for the spin -flip in GaAs quantum dots. We have calculated the rates for different mechanisms which are related to spin-orbit coupling and cause a spin-flip during the inelastic relaxation…

Mesoscale and Nanoscale Physics · Physics 2009-10-31 Alexander V. Khaetskii , Yuli V. Nazarov

We study the electron spin dynamics in p-type GaAs doped with magnetic Mn acceptors by means of time-resolved pump-probe and photoluminescence techniques. Measurements in transverse magnetic fields show a long spin relaxation time of 20 ns…

Materials Science · Physics 2009-07-17 I. A. Akimov , R. I. Dzhioev , V. L. Korenev , Yu. G. Kusrayev , E. A. Zhukov , D. R. Yakovlev , M. Bayer

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

Hole spins in semiconductors are a potential qubit alternative to electron spins. In nuclear-spin-rich host crystals like GaAs, the hyperfine interaction of hole spins with nuclei is considerably weaker than that for electrons, leading to…

We study the doping evolution of spin excitations in a 1D Hubbard model and its downfolded spin Hamiltonians, by using exact diagonalization combined with cluster perturbation theory. In all models, we observe hardening (softening) of spin…

Strongly Correlated Electrons · Physics 2019-05-08 Ekaterina M. Pärschke , Yao Wang , Brian Moritz , Thomas P. Devereaux , Cheng-Chien Chen , Krzysztof Wohlfeld

We have studied the Faraday rotation and ellipticity signals in ensembles of singly-charged (In,Ga)As/GaAs quantum dots by pump-probe spectroscopy. For degenerate pump and probe we observe that the Faraday rotation signal amplitude first…

Mesoscale and Nanoscale Physics · Physics 2010-11-09 M. M. Glazov , I. A. Yugova , S. Spatzek , A. Schwan , S. Varwig , D. R. Yakovlev , D. Reuter , A. D. Wieck , M. Bayer

The relaxation process of electron spin in systems of electrons interacting with piezoelectric deformation phonons that are mediated through spin-orbit interactions was interpreted from a microscopic point of view using the formula for the…

Mesoscale and Nanoscale Physics · Physics 2015-06-22 Nam Lyong Kang

The observation of coherent quantum transport phenomena in metals and semiconductors is limited by the eventual loss of phase coherence of the conducting electrons. We use the weak localization effect to measure the low-temperature…

Mesoscale and Nanoscale Physics · Physics 2010-08-27 M. Eshkol , E. Eisenberg , M. Karpovski , A. Palevski

We present a real-time abinitio description of optical orientation in bulk GaAs due to the coupling with an ultrashort circular polarized laser source. The injection of spin polarized electrons in the conduction band is correctly…

Materials Science · Physics 2020-10-07 Marco D'Alessandro , Davide Sangalli

Electron spin coherence has been generated optically in n-type modulation doped (In,Ga)As/GaAs quantum dots (QDs) which contain on average a single electron per dot. The coherence arises from resonant excitation of the QDs by…

Full electric-field control of spin orientations is one of the key tasks in semiconductor spintronics. We demonstrate that electric field pulses can be utilized for phase-coherent +/- pi spin rotation of optically generated electron spin…

Materials Science · Physics 2012-10-05 S. Kuhlen , K. Schmalbuch , M. Hagedorn , P. Schlammes , M. Patt , M. Lepsa , G. Güntherodt , B. Beschoten

Time-resolved pump-probe measurements were made at variable heat accumulation in Co/Pd superlattices. Heat accumulation increases the baseline temperature and decreases the equilibrium magnetization. Transient ultrafast demagnetization…

Mesoscale and Nanoscale Physics · Physics 2018-05-09 F. Hoveyda , E. Hohenstein , R. Judge , S. Smadici

We report on lateral spin-caloric transport (LSCT) of electron spin packets which are optically generated by ps laser pulses in the non-magnetic semiconductor n-GaAs at $T\leq35$K. LSCT is driven by a local temperature gradient induced by…

Mesoscale and Nanoscale Physics · Physics 2018-05-04 Stefan Göbbels , Gernot Güntherodt , Bernd Beschoten

A spin transport model is employed to study the effects of spin dephasing induced by diffusion-driven transit-time uncertainty through semiconductor spintronic devices where drift is the dominant transport mechanism. It is found that in the…

Materials Science · Physics 2009-11-13 Biqin Huang , Ian Appelbaum

The periodic optical orientation of electron spins in (In,Ga)As/GaAs quantum dots leads to the formation of electron spin precession modes about an external magnetic field which are resonant with the pumping periodicity. As the electron…

Mesoscale and Nanoscale Physics · Physics 2019-08-15 E. Evers , V. V. Belykh , N. E. Kopteva , I. A. Yugova , A. Greilich , D. R. Yakovlev , D. Reuter , A. D. Wieck , M. Bayer

We perform an investigation on the spin relaxation for $n$-type ZnO (0001) quantum wells by numerically solving the kinetic spin Bloch equations with all the relevant scattering explicitly included. We show the temperature and electron…

Mesoscale and Nanoscale Physics · Physics 2009-10-10 C. Lü , J. L. Cheng

The thermal conductivity of electron-doped Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$ single crystals is investigated below 200K, with an emphasis on the behavior near the magnetic and superconducting (T_c) transition temperatures. An enhancement of…

Superconductivity · Physics 2013-08-09 Andrew F. May , Michael A. McGuire , Jonathan E. Mitchell , Athena S. Sefat , Brian C. Sales

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 report electronic control and measurement of an imbalance between spin-up and spin-down electrons in micron-scale open quantum dots. Spin injection and detection was achieved with quantum point contacts tuned to have spin-selective…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 E. J. Koop , B. J. van Wees , D. Reuter , A. D. Wieck , C. H. van der Wal

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 the spin diffusion profile. A further means…

Materials Science · Physics 2008-10-27 J. -H. Quast , G. V. Astakhov , W. Ossau , L. W. Molenkamp , J. Heinrich , S. Hofling , A. Forchel
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