Electron charge and spin delocalization revealed in the optically probed longitudinal and transverse spin dynamics in $n$-GaAs

Abstract

The evolution of the electron spin dynamics as consequence of carrier delocalization in $n$-type GaAs is investigated by the recently developed extended pump-probe Kerr/Faraday rotation spectroscopy. We find that isolated electrons localized on donors demonstrate a prominent difference between the longitudinal and transverse spin relaxation rates in magnetic field, which is almost absent in the metallic phase. The inhomogeneous transverse dephasing time $T_2^{\ast }$ of the spin ensemble strongly increases upon electron delocalization as a result of motional narrowing that can be induced by increasing either the donor concentration or the temperature. An unexpected relation between $T_2^{\ast }$ and the longitudinal spin relaxation time $T_1$ is found, namely that their product is about constant, as explained by the magnetic field effect on the spin diffusion. We observe a two-stage longitudinal spin relaxation which suggests the establishment of spin temperature in the system of exchange-coupled donor-bound electrons.

arXiv comment6 pages, 4 figures

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• Extended pump-probe Faraday rotation spectroscopy of the submicrosecond electron spin dynamics in n-type GaAs
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• Longitudinal spin-relaxation of donor-bound electrons in direct bandgap semiconductors
• Millisecond spin-flip times of donor-bound electrons in GaAs
• Closing the gap between spatial and spin dynamics of electrons at the metal-to-insulator transition

Cited by in corpus (7)

• Increased sensitivity of spin noise spectroscopy using homodyne detection in $n$-doped GaAs
• Quantum Interference Controls the Electron Spin Dynamics in n-GaAs
• Unveiling the electron-nuclear spin dynamics in an n-doped InGaAs epilayer by spin noise spectroscopy
• Electron-induced nuclear magnetic ordering in n-type semiconductors
• Anomalous magnetic suppression of spin relaxation in a two-dimensional electron gas in a GaAs/AlGaAs quantum well
• Optical detection of electron spin dynamics driven by fast variations of a magnetic field: a simple method to measure $T_1$, $T_2$, and $T_2^{\ast }$ in semiconductors
• Long-lived electron spin coherence in Ga-doped crystals at room temperature