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Detection of nuclear magnetization by Faraday rotation
Auteur(s): Vladimirova M., Giri R., Cronenberger S., Scalbert D., Bloch Jacqueline, Lemaître Aristide, Kavokin K., Glazov Mikxail
Conference: PLMCN 14 (Hersonissos, GR, 2013-05-27)
Ref HAL: hal-00835618_v1
Exporter : BibTex | endNote
Résumé: We report on the nondestructive measurement of nuclear magnetization in n-GaAs via cavity enhanced Faraday rotation. In contrast with the existing optical methods, this detection scheme does not require the presence of detrimental out-of-equilibrium electrons. Specific mechanisms of the Faraday rotation are identified for (i) nuclear spins situated within the localized electron orbits, they are characterized by fast dynamics, (ii) all other nuclear spins in the sample characterized by much slower dynamics. Our results suggest, that even in degenerate semiconductors nuclear spin relaxation is limited by the presence of localized electron states and spin diffusion, rather than by Korringa mechanism.
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Long coherence time of isolated Mn spin in CdTe revealed by pump-probe experiment
Auteur(s): Andreev S., Cronenberger S., Scalbert D., Vladimirova M.
Conference: International School on Spin Optronics (ISSO 2) (Saint Pétersbourg, RU, 2012-07-10)
Ref HAL: hal-00816110_v1
Exporter : BibTex | endNote
Résumé: We report time-resolved Kerr rotation experiments on bulk CdMnTe with very low Mn concentration. We observe spin beatings which are the result of a complex spin dynamics of the d-electrons in the hyperfine field of their nucleus and the tetragonal crystal field. We find the transverse Mn spin relaxation time to increase with the increase of the effective temperature of Mn subsystem. At higher temperatures we measure T2 up to 12 ns, which is much longer than any previously measured values.
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Fine and hyperfine structure of isolated Mn in CdTe revealed by pump-probe experiments
Auteur(s): Andreev S., Cronenberger S., Vladimirova M., Scalbert D., Nawrocki Michal
Conference: International Conference on the Physics of Semiconductors (Zurich, CH, 2012-07-29)
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Faraday rotation induced by spin polarized electrons and nuclei in n-GaAs microcavity
Auteur(s): Giri R., Cronenberger S., Vladimirova M., Scalbert D., Kavokin Kirill, Lemaitre Aristide, Bloch Jacqueline
Conference: Internationale COnference on the physics of semiconductors (Zurich, CH, 2012-07-29)
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Optical Pump-Probe Detection of Manganese Hyperfine Beats in (Cd,Mn)Te Crystals
Auteur(s): Cronenberger S., Vladimirova M., Andreev S., Lifshits M., Scalbert D.
(Article) Publié:
Physical Review Letters, vol. 110 p.077403 (2013)
Ref HAL: hal-00789507_v1
DOI: 10.1103/PhysRevLett.110.077403
WoS: 000314871300011
Exporter : BibTex | endNote
16 Citations
Résumé: Optical pump-probe experiments reveal spin beats of manganese ions in (Cd,Mn)Te, due to hyperfine and crystal fields. At "magic" orientations of the magnetic field, the effect of local crystal field is strongly suppressed. In this case, the spin precession of Mn2+ embedded in the lattice approaches the precession expected for the free ion. Following optical excitation, regular spin pulses show up, revealing the one-to-one correspondence between precession frequency and Mn2+ nuclear spin state. The period of the spin pulses accurately determines the hyperfine constant |A|=705 neV. The manganese spin coherence time up to T2Mn≃15 ns is measured for a manganese concentration x=0.0011.
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Giant photoinduced Faraday rotation due to the spin-polarized electron gas in an n-GaAs microcavity
Auteur(s): Giri R., Cronenberger S., Vladimirova M., Scalbert D., Kavokin K., Glazov Mikhael, Nawrocki Michal, Lemaître Aristide, Bloch Jacqueline
(Article) Publié:
-Physical Review B Condensed Matter And Materials Physics (1998-2015), vol. 85 p.195313 (2012)
Ref HAL: hal-00702950_v1
DOI: 10.1103/PhysRevB.85.195313
WoS: 000303859100009
Exporter : BibTex | endNote
28 Citations
Résumé: Faraday rotation up to 19∘ in the absence of an external magnetic field is demonstrated in an n-type bulk GaAs microcavity under circularly polarized optical excitation. This strong effect is achieved because (i) the spin-polarized electron gas is an efficient Faraday rotator and (ii) the light wave makes multiple round trips in the cavity. We introduce a concept of Faraday rotation cross section as a proportionality coefficient between the rotation angle, electron spin density and optical path and calculate this cross section for our system. From independent measurements of photoinduced Faraday rotation and electron spin polarization we obtain quantitatively the cross section of the Faraday rotation induced by free electron spin polarization σFexp=−(2.5±0.6)×10−15 rad×cm2 for photon energy 18 meV below the band gap of GaAs, and electron concentration 2×1016 cm−3. It appears to exceed the theoretical value σFth=−0.7×10−15 rad×cm2, calculated without fitting parameters. We also demonstrate the proof-of-principle of a fast optically controlled Faraday rotator.
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n-GaAs microcavity as an efficient Faraday rotator
Auteur(s): Scalbert D., Cronenberger S., Vladimirova M., Bloch Jacqueline, Lemaître Aristide
Conference: Optics of Excitons in Confined Systems 12 (Paris, FR, 2011-09-11)
Ref HAL: hal-00627898_v1
Exporter : BibTex | endNote
Résumé: Faraday rotation is a well-known magneto-optical phenomenon: polarization plane of the light wave is rotated upon transmission through a magnetized medium. It is believed that most efficient Faraday rotators are transparent magnetic materials, such as rare-earth doped glasses and garnets, as well as diluted magnetic semiconductors, where magnetic ions create strong magnetization. In contrast, in conventional non-magnetic semiconductors the rotation due to magnetization of electron gas in the presence of equivalent magnetic field is much smaller. We show, that using optical orientation of electron gas in GaAs confined in a microcavity (Q=50000) it is possible to reach the rotation angles larger than 10° at only 1% spin polarization of the electron gas and in the absence of magnetic field ( Fig. 1 ). This strong rotation exceeds by orders of magnitude the rotation ever measured in bulk n-GaAs samples of similar concentration () [1] [2] . We deduce from these experiments the Verdet constant associated with the electron spin polarization density. This also allows for the direct detection of the extremely slow electron spin polarization decay (~250 ns) in the absence of the pump ( Fig. 2 ). It suggests that spin relaxation time in the dark can be much longer than the relaxation time extracted from Hanle depolarization in either photoluminescence [3] or Faraday rotation ( Fig. 1 ) experiments.
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