Suppressed spin dephasing for 2D and bulk electrons in GaAs wires due to engineered cancellation of spin-orbit interaction terms

We report a study of suppressed spin dephasing for quasi-one-dimensional electron ensembles in wires etched into a GaAs/AlGaAs heterojunction system. Time-resolved Kerr-rotation measurements show a suppression that is most pronounced for wires along the [110] crystal direction. This is the fingerprint of a suppression that is enhanced due to a strong anisotropy in spin-orbit fields that can occur when the Rashba and Dresselhaus contributions are engineered to cancel each other. A surprising observation is that this mechanisms for suppressing spin dephasing is not only effective for electrons in the heterojunction quantum well, but also for electrons in a deeper bulk layer.Comment: 5 pages, 3 figure

Optical probing of spin dynamics of two-dimensional and bulk electrons in a GaAs/AlGaAs heterojunction system

We present time-resolved Kerr rotation measurements of electron spin dynamics in a GaAs/AlGaAs heterojunction system that contains a high-mobility two-dimensional electron gas (2DEG). Due to the complex layer structure of this material the Kerr rotation signals contain information from electron spins in three different layers: the 2DEG layer, a GaAs epilayer in the heterostructure, and the underlying GaAs substrate. The 2DEG electrons can be observed at low pump intensities, using that they have a less negative g-factor than electrons in bulk GaAs regions. At high pump intensities, the Kerr signals from the GaAs epilayer and the substrate can be distinguished when using a barrier between the two layers that blocks intermixing of the two electron populations. This allows for stronger pumping of the epilayer, which results in a shift of the effective g-factor. Thus, three populations can be distinguished using differences in g-factor. We support this interpretation by studying how the spin dynamics of each population has its unique dependence on temperature, and how they correlate with time-resolved reflectance signals.Comment: 14 pages, 7 figure

Spin-dephasing anisotropy for electrons in a diffusive quasi-1D GaAs wire

We present a numerical study of dephasing of electron spin ensembles in a diffusive quasi-one-dimensional GaAs wire due to the D'yakonov-Perel' spin-dephasing mechanism. For widths of the wire below the spin precession length and for equal strength of Rashba and linear Dresselhaus spin-orbit fields a strong suppression of spin-dephasing is found. This suppression of spin-dephasing shows a strong dependence on the wire orientation with respect to the crystal lattice. The relevance for realistic cases is evaluated by studying how this effect degrades for deviating strength of Rashba and linear Dresselhaus fields, and with the inclusion of the cubic Dresselhaus term

Comparison of photoacoustic spectroscopy and gas chromatography for the assessment of soil greenhouse gases emissions.

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