Coherent electrical spin injection and detection across ferromagnet-semiconductor interfaces

We propose to perform time- and spatially-resolved studies of coherent spin currents in n-doped semiconductors. In a first focus, we will use ultrafast current pulses to inject electron spins from a ferromagnet into a semiconductor. We have recently demonstrated the coherence of this electrical spin injection process by the detection of subsequent spin precession in the semiconductor using phase-sensitive time-resolved MOKE as a probe. Spin dephasing and spin transport times as well as the role of hot carrier relaxation during the injection process shall be investigated with this technique. We suggest extending this method to lateral devices which have ferromagnetic source and drain contacts to obtain spatio-temporal maps of the coherent spin currents with both spin and phase information in order to extract spin diffusion and accumulation times and length. In a second focus, we propose to explore methods for timedomain electrical detection schemes for coherent spin transport from the semiconductor back into the ferromagnet.