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June 23, 2008

Breakthrough could be significant step to faster Spintronic computers


click on the image for a larger version of the picture

Physicists at UC Riverside have made an accidental discovery in the lab that has potential to change how information in computers can be transported or stored. The thickness of MgO (Magnesium Oxide) can control the flow of electrons with different spin.

When the MgO interface is very thin, spin up electrons, represented in this image with an arrow to the right, are reflected back to the semiconductor. At an intermediate thickness of the interface, spin down electrons are reflected back to the semiconductor, resulting in a “spin reversal” that can be used to control current flow.


Inversion of Ferromagnetic Proximity Polarization by MgO Interlayers at Physics Review Letters by

Yan Li,1 Y. Chye,1 Y. F. Chiang,1 K. Pi,1 W. H. Wang,1 J. M. Stephens,2 S. Mack,2 D. D. Awschalom,2 and R. K. Kawakami1

1Department of Physics and Astronomy, University of California, Riverside, California 92521, USA 2Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106, USA

We investigate the spin-dependent reflection properties in Fe/MgO/GaAs heterostructures by optical pump-probe measurement of the ferromagnetic proximity polarization (FPP). As a function of MgO thickness, the FPP is initially enhanced (<2.0 Å) and then exhibits an unexpected sign reversal at ~5.0 Å. The identification of two competing thresholds in the intensity dependence of FPP and the observation of FPP sign reversal in Fe/Mg/GaAs suggest that the inversion of FPP is related to an interfacial bonding effect.



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