Electrical Detection of Spin Transport in Semiconductors

1. Electrical Detectionof 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 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 semiconductor electronics. Researchers at the University of Minnesota – led by Paul Crowell and Chris Palmstrom working in collaboration with Scott Crooker at the Magnet Lab’s Pulsed Field Facility at Los Alamos – have demonstrated a simple functional spintronic device in which spin-polarized electrons 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 electron spin precession in the semiconductor. Schematic of the spin transport device. Large arrows show the magnetization of the iron electrodes. The small arrows show the injected electron spins in the semiconductor. The electron spin orientation can be read out using an ordinary voltmeter (V), or with an optical Kerr microscope (shown focusing on the device). Lou, X.; Adelmann, C.; Crooker, S.A.; Garlid, E.S.; Zhang, J.; Reddy, K.S.M.; Flexner, S.D.; Palmstrom, C.J.; Crowell, P.A.Electrical Detection of Spin Transport in Lateral Ferromagnet-Semiconductor Devices, Nature Physics3,197 (2007).