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Electrical Detection of Spin Transport in Semiconductors

In semiconductor spintronics, the spin of the electron carries information for both storage and data processing. To some extent, the electron spin can be viewed as a miniature bar magnet that interacts with a magnetic field inside the semiconductor. The orientation of the bar magnet acts as a "bit" of information. Many laboratory demonstrations of spintronics have relied on sophisticated optical techniques for reading out the spin state of electrons. Future applications, however, will require a simple readout scheme using ordinary ferromagnetic materials (such as iron) and conventional electronics. IRG 3 graduate students Xiaohua Lou and Madhukar Reddy, IRG 3 postdoc Christoph Adelmann, and Professors Paul Crowell and Chris Palmstrøm have demonstrated a simple functional spintronic device in which spins are injected into a semiconductor channel from a ferromagnetic source and detected at a separate electrode. The measurement is completely electronic in character and is shown to be sensitive to the precession of the electron spin in the semiconductor. Working with collaborator Scott Crooker (Los Alamos National Laboratory), the IRG researchers have shown that their electronic device produces an output that is essentially identical to that obtained using more established optical techniques. This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-0212302. [Lou, X.; Adelmann, C.; Crooker, S.A.; Garlid, E.S.; Zhang, J.; Reddy, K.S.M.; Flexner, S.D.; Palmsøm, C.J.; Crowell, P.A. Electrical Detection of Spin Transport in Lateral Ferromagnet-Semiconductor Devices. Nature Physics 2007, 3, 197]