Technologists working in smoke filled labs have worked out a way to use electric fields to manipulate the spin property of electrons to store data permanently.
The breakthrough could improve random access memory (RAM) in computers, bring above a new generation of gizmos and bring about peace in our lunchtime.
The new kind of memory uses “tunnel magnetoresistance” or TMR. This is basically two thin layers of a magnetic material are separated from each other by an insulator.
The insulator does not allow electrons to pass unless some of the charge carriers sneak from one side to the other, often disguised as something quirky and quantum.
It also takes advantage of the intrinsic angular momentum of all electrons, which physicists call “spin”. According to physics there are two spin states an electron can be in: either “up” or “down”.
If most of the spins are oriented the same way in both magnetic layers of this TMR sandwich, then electrons tunnel much more easily than if one magnetic layer has mostly “up” spins and the other has “down” spins.
It can be used for rapid and repeated data writes, much like conventional memory, but also capable of permanently storing this data.
In the past TMR-based memory known as MRAM has needed strong magnetic fields to write data which means the powerbill suffers too much.
However boffins Vincent Garcia and Manuel Bibes changed all this with an insulator made out of barium titanate. This is fairly obvious to hacks who all know that spin usually involves a bar somewhere.
Now another set of boffins, Sergio Valencia and Florian Kronast have used X-ray absorption spectroscopy (XAS) to study the chemical composition of the magnetic layers of this sandwich.
Armed with this information they can use an electric field to switch the insulator in a way that influences the electron spins in the magnetic layers either side of it, thereby influencing the electron tunnelling as well.
Since the insulator keeps the same switched state when all current is removed, this model could be used to build PC memory that draws very little power and still stores data permanently. We are still not certain if the cat is dead or alive yet.