  Efforts to achieve efficient injection of spin-polarized electrons into a
semiconductor, a key prerequisite for developing electronics that exploit the
electron's spin degree of freedom, have so far met with limited success. Here
we report experimental studies of lateral spin injection and detection through
electrodeposited Fe/GaAs tunnel contacts. We demonstrate spin injection
efficiencies two orders of magnitude higher than for state-of-the-art contacts
fabricated via ultra-high-vacuum methods, including those with MgO or Al2O3
tunnel barriers. To account for this enhancement, we propose that an iron oxide
layer that forms at the Fe/GaAs interface during electrodeposition, being
magnetic, acts as a tunnel barrier with a spin-dependent height, presenting
quantum spin transport calculations for such systems. This serendipitous
discovery of greatly enhanced efficiency of spin injection into GaAs via
electrodeposited contacts introduces a promising new direction for the
development of practical semiconductor spintronic devices.
