Electrical spin injection in a ferromagnetic semiconductor heterostructure

Conventional electronics is based on the manipulation of electronic charge. An intriguing alternative is the field of 'spintronics: wherein the classi cal manipulation of electronic spin in semiconductor devices gives rise to the possibility of reading and writing non-volatile information through mag netism(1,2) Moreover, the ability to preserve coherent spin states in conve ntional semiconductors' and quantum dots(4),ay eventually enable quantum co mputing in the solid state(5,6). Recent studies have shown that optically e xcited electron spins can retain their coherence over distances exceeding 1 00 micrometres (ref. 7). But to inject spin-polarized carriers electrically remains a formidable challenge(8,9), Here we report the fabrication of all -semiconductor, light-emitting spintronic devices using III-V heterostructu res based on gallium arsenide. Electrical spin injection into a nonmagnetic semiconductor is achieved (in zero magnetic field) using a p-type ferromag netic semiconductor(10) as the spin polarizer. Spin polarization of the inj ected holes is determined directly from the polarization of the emitted ele ctroluminescence following the recombination of the holes with the injected (unpolarized) electrons.