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Penn Researchers Discover New Chiral Property of Silicon, With Photonic Applications


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By shining lasers with different polarizations on their device, the researchers could make current flow in different directions.

Researchers at the University of Pennsylvania say they have discovered a property of silicon that combines aspects of photonic and spintronic computing.

Credit: Penn News

University of Pennsylvania (UPenn) researchers say they have discovered a property of silicon that combines aspects of photonic and spintronic computing.

The researchers demonstrated a silicon-based photonic device that is sensitive to the spin of the photons in a laser shined on one of its electrodes. They note its chiral property is a function of the geometric relationship between the pattern of atoms on the surface of silicon nanowires and how electrodes placed on those wires intersect them.

The interaction between the semiconducting silicon and the metallic electrodes produces an electric field at an angle that breaks the mirror symmetry that silicon typically exhibits. The chiral property sends electrons in one direction or the other down the nanowire depending on the polarity of the light that hits the electrodes.

"Typically, materials with heavy elements show this property due to their spins strongly interacting with electron's orbital motion, but we have demonstrated this effect on the surface of silicon, originating only from the electron's orbital motion," says UPenn professor Ritesh Agarwal.

He notes this new class of materials are electrical insulators on their interiors, but conduct electricity on their surfaces.

From Penn News
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