Lawrence Berkeley National Laboratory Materials Science Division researchers have made a major advancement in spintronics by controlling the spin states of highly mobile electrons at different locations in a semiconductor and turning the collective state on and off as desired. This could lead to more efficient spin transistors and other devices, as controlling and measuring the magnetic fields of electrons with aligned spins could allow faster data recovery and lower power consumption.
In semiconductors, a "gas" of free electrons moving through the crystal lattice reacts to the electric fields of the atoms it encounters. Individual electron spins fluctuate wildly in response to different fields and their orientation quickly becomes random. By creating a two-dimensional electron gas by confining the electrons in a "quantum well," charged particles were forced to travel in a plane. When electrons move through that plane, their interaction with passing atoms causes them to precess, eventually exchanging initial spin-up states for spin-down states. The researchers induced a "helical" spin state in the electron gas and measured how the collective spin state evolved.
From Lawrence Berkeley National Laboratory
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