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“Currently, we are looking at logic schemes for spintronics, so we are moving from memory and storage to processing,” says Mubashir Hussain.

Spintronic devices have created enormous advances in microelectronics, leading to faster, instant-on start times and orders-of-magnitude increases in data storage capacity. Spintronics is short for spin transport electronics – electronic devices that use the spin of an electron to carry information.

Currently, semiconductor devices work using charge, with positive and negative charges denoting the 1s and 0s of binary language. “But electrons have another degree of freedom,” says Mubashir Hussain, co-coordinator of UIT, “and you can also control their spin, or their magnetic orientation.”

Spin then becomes another information carrier. There are numerous advantages to the technique. Information stored by charge is volatile; it disappears as soon as the current is cut off. This is why people can lose hours of work if there is a power cut and they forgot to save.

Instant-on devices
But in the proper environment, spin is non-volatile. In magnetic material, once you switch spin to up or down it stays in that orientation until you switch it back.

“It means that when you cut the current, everything stays as it is,” explains Hussain. This could lead to instant-on devices.

Spintronic devices also use little power. “It takes a very low current to switch spin, which makes these devices very efficient,” Mubashir notes. And, at least theoretically, spintronic devices could have very high switching speed.

“We have not proven this in the lab yet, but many results in the theory have already been proven so high switching speeds [are quite likely],” Hussain states. It could mean spintronic devices reach the terahertz range, which is pretty fast.

Reusing the wheel
Finally, spintronic devices have excellent scalability, because they are based on ferromagnetic semiconductors, and semiconductor manufacturing technologies are well established.

“There would still be engineering challenges – you would have to adapt current manufacturing techniques to these materials – but we would not have to reinvent the wheel,” reveals Hussain.

Most existing spintronic devices use metals rather than semiconductors, mainly because researchers have yet to find a semiconducting material that works at room temperatures. The search is on, and researchers are confident they will find an appropriate material.

“Currently, the record is 185 Kelvin (-88°C), held by one of Nasir. “But we are reasonably sure the temperature problem can be solved, because the theory has predicted values in the 100s of degrees centigrade for some materials.”

Spintronic devices are sufficiently compelling to deserve sustained research, and Nasir set out to develop device demonstrators. Rather than tackling the room temperature problem directly, Nasir intended to prepare the way for when an appropriate room temperature material is found.

Four strands
“Normally, you find a property or material and then develop a device to exploit it. We wanted to speed up the process by developing the concept devices in a lab now so they are ready when the appropriate material is found,” says Hussain.

There were four strands to the team’s work: writing information to ferromagnetic semiconductors, retrieving it, high-speed switching between different states and the theoretical modelling of the devices to explain their operation and allow for optimisation.

“We were essentially looking at devices for memory and storage of information using ferromagnetic semiconductors,” Hussain notes. The project was very successful, and generated a lot of interest from industry.