Superfast lasers open a shortcut to hard drives of the future Premium

Scientists study ultra-fast spin currents to improve data storage and manipulation in computers using electrons' spin states.

You’re watching Chennai Super Kings play Mumbai Indians at the Wankhede. The stands are packed and the atmosphere is electric. In the excitement, a bunch of people in one of the stands starts a Mexican wave. Everyone is eager to participate. At just the right moment, hundreds of people stand up and sit down in unison, giving the wave a full and fervent expression. 

The Mexican wave is a type of wave that appears to propagate through a medium when the medium’s constituents are sequentially displaced from and restored to their original positions.

In the same way, let’s imagine a spin current.

Every electron particle has an intrinsic property called quantum spin, or just spin for short. It represents some angular momentum carried by the particle. At any given moment it can be measured to have one of two values, colloquially called up and down. A spin current flows through a medium when electrons transmit a spin state — say, up — in quick succession before reverting to their original state (in this case down).

That is, when a spin current moves through a material, it implies a Mexican wave of a particular spin state moving through the material. The electrons themselves aren’t displaced, however.

Scientists are interested in spin currents because the electrons’ up and down spin states can represent 0s and 1s, to store and retrieve data in a computer’s hard drive. Spintronic drives of the future are expected to be able to store more data than existing drives, manipulate the data faster, and consume less energy.

In a study published in the journal Physical Review Letters on September 6, an international team of researchers reported an important advance on this front.