This invention relates to spintronic devices--and electronic devices comprising them, such as spin valves, spin tunnel junctions and spin transistors--which utilize a layer comprised of an array of aligned carbon nanontubes. A spintronic device includes, a bottom electrode, a first ferromagnetic layer, a CNT array, a second ferromagnetic layer and a top electrode.
 This work is supported by U.S. Department of Energy Grant No. DE-FG02-01 ER45931, U.S. Defense Advance Projects Research Agency (DARPA) through Office of Naval Research (ONR) (Grant No. N00014-O.sub.2-1-0593), and U.S. Army Research Office (ARO) (Grant No. DAAD 19-01-1-0562).