Tuesday, September 25, 2007

Quantum Spin Hall Effect

This certainly would be a major advancement in spintronics if it can be verified and manufactured. A group at Stanford and at University of W├╝rzburg have fabricated a spintronic device based on the spin states of the semiconductor, whereby the transport in this case is not the charges, but rather the spin "current" of the electrons.

Using special semiconductor material made from layers of mercury telluride and cadmium telluride, the experimenters employed quantum tricks to align the spin of electrons like a parade of tops spinning together. Under these extraordinary conditions, the current flows only along the edges of the sheet of semiconductor. Interestingly, electrons with identical spins travel in the same direction together, while electrons with the opposite spin move in the opposite direction. Unlike existing semiconductors, this unusual electric current does not generate destructive heat through dissipation of power or the collision of electrons with impurities in the semiconducting material.

So there isn't your usual heat dissipation via Ohmic heating. This certainly is the next logical step in semiconductor physics.

And there are people who can't figure out the use of quantum mechanics? :)


1 comment:

minorwork said...

A link neglected mention of plasma as a state of matter. I am under the impression that it is a natural state and so common that descriptions claim the universe is 99% plasma.

Also, would a relativistic pinch occur in opposing flows in this spin current? Commonly known as a magnetic field. I have much to study here.