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Effets spin-orbite géants sur les modes collectifs de spin de puits quantiques

Abstract : We have studied the effects of spin-orbit coupling in doped semiconductor quantum wells (GaAs and CdMnTe) with electronic Raman scattering. In these structures exist intrinsic magnetic fields (Dresselhaus and Rashba). These fields offer attractive means to manipulate the electron spin, but contribute also to spin relaxation, through their dependence on the electronic wavevector (D'yakonov-Perel' mechanism). We show that for the collective spin modes of quantum wells, the destructive D'yakonov-Perel' scenario is transformed into a constructive scenario: Coulombic interactions lead to the emergence of a collective spin-orbit field, proportional to the excitation wavector, and several times enhanced with respect to the single-particle spin-orbit fields. We first demonstrate these giant spin-orbit effects on the intersubband spin plasmon, in GaAs quantum wells. The collective spin-orbit field, which produces a fine structure splitting of the plasmon spectrum, is superposed to an external magnetic field and mapped in momentum space. Then, we study the intrasubband spin wave of the spin-polarized electron gas, in diluted magnetic quantum wells of CdMnTe. Here the collective spin-orbit field adds to the giant Zeeman field of the compound. We measure the enhancement factor of the collective spin-orbit field. Finally, we determine the dependence of the enhancement factor on the electronic density, and demonstrate the ability to control the amplitude of the collective spin-orbit field through above-barrier illumination.
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https://tel.archives-ouvertes.fr/tel-01020564
Contributor : Florent Baboux Connect in order to contact the contributor
Submitted on : Tuesday, July 8, 2014 - 11:38:23 AM
Last modification on : Saturday, January 15, 2022 - 3:44:40 AM
Long-term archiving on: : Wednesday, October 8, 2014 - 1:00:24 PM

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  • HAL Id : tel-01020564, version 1

Citation

Florent Baboux. Effets spin-orbite géants sur les modes collectifs de spin de puits quantiques. Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]. Université Pierre et Marie Curie - Paris VI, 2013. Français. ⟨tel-01020564⟩

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