Oblique Hanle measurements of InAs∕GaAs quantum dot spin-light emitting diodes

We report on studies of electrical spin injection from ferromagnetic Fe contacts into semiconductor light emitting diodes containing single layers of InAs∕GaAs self-assembled quantum dots (QDs). An oblique magnetic field is used to manipulate the spin of the injected electrons in the semiconductor. This approach allows us to measure the injected steady-state spin polarization in the QDs, Pspin as well as estimate the spin losses in the QD spin detector. After subtraction of magneto-optical effects not related to spin injection, we measured a Pspin of 7.5% at 15 K and estimated an injected spin polarization before QD recombination of around 20%.