Saturday, December 06, 2008

US Patent 7459682 - Nanowire array spin-polarized electron source

One variety of nanoscale detection devices is spin polarized scanning probe microscopy which uses the spin of electrons emitted from a sharp tip to characterize magnetic phenomena on the nanoscale. However continuous emission is difficult at room temperature. This patent from Hon Hai Precision and Tsinghua University teaches using III-V nanowire arrays to achieve such microscopy at room temperature. Claim 1 reads:

1. A spin-polarized electron source, comprising:

a cathode;

a one-dimensional nanostructure comprised of a compound semiconductor with local polarized gap states, the one-dimensional nanostructure including a first end portion electrically connected with the cathode and a second end portion directed away from the cathode, the second end portion of the one-dimensional nanostructure functioning as a polarized electron emission tip and being configured for emitting a spin-polarized electron current/beam under an effect of selectably one of a magnetic field induction and a circularly polarized light beam excitation when a predetermined negative bias voltage is applied to the cathode.

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