All-electric spintronic semiconductor devices created

LONDON - A team of physicists has come closer to making electron spin the universal language of computation - they are the first to develop a simple, all-electric method to both generate and detect spin currents within a standard semiconductor.

Spintronics devices could use electron spin to perform both operations, promising to speed up a computer’s load and boot times.

In their recent experiment, Paul Crowell of the University of Minnesota in Minneapolis and his team sent a current through a gallium arsenide semiconductor, doped with silicon impurities and indium to enhance the spin-splitting effect.

The impurities were contained within a 2.5-micrometre-deep, 30-micrometre-wide channel: as electrons pinged off the impurities to right or left, they gathered at the channel’s edges, where they passed one of two iron electrodes bordering each side of the channel.

The electron’s spin gives it a tiny magnetic moment, and the moments of the right and left-spinning electrons point in opposite directions. The electrons spinning inside the two iron electrodes only “see” the electrons in the semiconductor that share their alignment - in this case, the right-spinning electrons.

Because many of those right-spinning electrons gathered at one side of the semiconductor channel - while left-spinning electrons gather at the other side - one of the iron electrodes sees more negative charge than the other, establishing a voltage between the two and giving the first electrical measurement of the spin Hall effect.

“You can actually just hook up wires to the semiconductor. That makes things a lot more flexible,” New Scientist quoted Crowell as saying.

However, a long road still lies ahead before spintronic PCs hit the marketplace. These spin currents arise at room temperature, but Crowell’s group’s approach needs cold temperatures to keep the spin-divided electrons at the side of the channel long enough to be measured.

A perhaps greater challenge will be to divide the electron spins more efficiently - in the present study, only a few of every hundred electrons separated according to their spin. (ANI)