Time-resolved Kerr rotation spectroscopy as a function of pump-probe distance, voltage and magnetic field is used to measure the momentum-dependent spin splitting energies in GaAs and InGaAs epilayers. The strain of the samples can be reproducibly controlled in the cryostat using three-and four-point bending applied with a mechanical vise. We find that the magnitude of the spin splitting increases linearly with applied tension and voltage. A strain-drift-diffusion model is used to relate the magnitude of the measured spin-orbit splitting to the amount of strain in the sample.PACS numbers: 71.70. Ej, 71.70.Fk, 72.25.Dc, 72.25.Rb Potential applications in spintronics 1 and quantum information processing 2 rely upon an understanding of the effect of electric fields and strain on electron spins. Strain reduces the symmetry of a crystal, which introduces momentum k-linear terms to the Dresselhaus 3 and Bychkov-Rashba 4 spin splittings. These strain-induced effective magnetic fields can be used to generate electron spin polarization electrically 6 and coherently manipulate spins using electric fields and in the absence of magnetic fields 5 , but they also contribute to more efficient spin relaxation 7 . In addition, recent steady-state measurements 8,9 have shown that the spatial period of strain-induced spin precession is independent of the applied electric field, which demonstrates the robustness of strain-induced spin precession for applications in functional spin-based devices.Here we employ mechanical three-and four-point bending to tune the tensile strain of GaAs and In-GaAs epilayers while performing low-temperature timeresolved magneto-optical spectroscopy to determine the magnitude of the strain-induced spin splitting. The samples are contacted so that an in-plane electric field can be applied to impart an average drift velocity to the optically-excited electron spins.Kerr rotation measurements as a function of magnetic field and pump-probe distance are performed for different applied electric fields, and we observe that the spin splitting increases with increasing drift velocity and tensile strain. Unlike previous measurements that introduced strain through heterostructure engineering and latticemismatched growth 5 , these measurements are able to map out the strain dependence in a single sample and without the complications of strain relaxation. The vise geometry allows for repeatable tensioning of samples and precise control over the strain level.The samples are grown using molecular beam epitaxy on semi-insulating (001) GaAs substrates. We examine both n-doped GaAs and InGaAs epilayers. The GaAs samples are comprised of 100 nm undoped GaAs buffer layer, 400 nm Al 0.7 Ga 0.3 As, and a 500 nm Si-doped GaAs epilayer. Samples with carrier densities of 2 × 10 16 cm −3 and 4 × 10 16 cm −3 were measured, but since they exhibit qualitatively similar behavior, we show only data for the 2 × 10 16 cm −3 n-GaAs sample in this paper. The InGaAs sample is composed of 300 nm of growth-interrupted GaAs buffer layer, 50...

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The effect of uniaxial tensile strain on spin coherence in n-type GaAs epilayers is probed using time-resolved Kerr rotation, photoluminescence, and optically-detected nuclear magnetic resonance spectroscopies. The bandgap, electron spin lifetime, electron g-factor, and nuclear quadrupole splitting are simultaneously imaged over millimeter scale areas of the epilayers for continuously varying values of strain. All-optical nuclear magnetic resonance techniques allow access to the strain induced nuclear quadrupolar resonance splitting in field regimes not easily addressable using conventional optically-detected nuclear magnetic resonance.