A team of researchers from Virginia Commonwealth University has invented the most power-friendly integrated circuit so far, by combining spintronics and straintronics. The circuit needs so little energy to run that it doesn’t even need a battery – it works by tapping the ambient energy.
Spintronics harnesses the natural spin (up/down) of electrons. This up/down orientation of the spin can be used to encode bits (0 or 1) and can be controlled by means of a magnetic field or a spin-polarized current pulse. It is to be noted that spintronics uses far less energy than current charge-based circuits, but so far it could not be used because of the issues that appear when trying to up-scale it to usable processing speeds.
At those speeds (high clock frequencies), much of that energy savings is lost in the mechanism through which the energy from the outside world is transferred to the magnet.
The VCU team uses a composite material called “multiferroics“. These composite structures consist of a layer of piezoelectric material with intimate contact to a magnetostrictive nanomagnet (one that changes shape in response to strain).
When a tiny voltage is applied across the structure, it generates strain in the piezoelectric layer, which is then transferred to the magnetostrictive layer. This strain rotates the direction of magnetism, achieving the flip. By properly choosing materials, the energy dissipated can be as low as 0.4 attojoules, or about a billionth of a billionth of a joule.
The applications of this spintronics and straintronics – enabled circuitry would be endless, from ultra-low power/high density magnetic logic and memory systems to implantable medical devices that charge themselves from the body motion. Not to mention the power savings a computer made with such a technology would have to offer.