Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 5: Spintronics: mainly interfaces and heterostructures

HL 5.6: Vortrag

Montag, 11. März 2013, 10:45–11:00, H16

Electric suppression of spin dephasing in GaAs (111) quantum wells — •Alberto Hernandez-Minguez, Klaus Biermann, Rudolph Hey, and Paulo V. Santos — Paul-Drude-Institut für Festkörperelektronik

Diakonov-Perel spin dephasing is a major mechanism limiting the electron spin lifetime in III-V zincblende quantum wells: electrons with different wavevector experience different effective magnetic fields associated to spin-orbit interaction (SOI). Their spins will then precess at different frequencies, thus leading to a reduction of the initial spin polarization of an electron ensemble. In this contribution, we demonstrate that this dephasing can be effectively suppressed in GaAs (111) quantum wells by applying an electric field. The suppression has been attributed to the compensation, for all electron wavevectors simultaneously, of the intrinsic SOI associated to the bulk inversion asymmetry (BIA) of the GaAs lattice by a structural induced asymmetry (SIA) SOI term induced by the electric field [1]. We provide direct experimental evidence for this mechanism by demonstrating the transition between the BIA-dominated to a SIA-dominated regime via photoluminescence measurements carried out over a wide range of applied fields in quantum wells embedded in a n-i-p structure. Spin lifetimes exceeding 100 ns are obtained near the compensating electric field [2], thus making GaAs (111) quantum wells excellent candidates for spin-based quantum information processing.

[1] X. Cartoixà et al., Phys. Rev. B 71, 045313 (2005).

[2] A. Hernández-Mínguez et al., Phys. Rev. Lett., accepted.