Magneto-electric transistor demonstrated

Along with curbing the energy consumption of any microelectronics that incorporate it, say the researchers, the new transistor design could reduce the number of transistors needed to store certain data by as much as 75%, leading to smaller devices. According to the researchers, it could also lend those microelectronics “steel-trap” memory that remembers exactly where its users leave off, even after being shut down or abruptly losing power.

“The traditional integrated circuit is facing some serious problems,” says Peter Dowben, Charles Bessey Professor of physics and astronomy at Nebraska. “There is a limit to how much smaller it can get. We’re basically down to the range where we’re talking about 25 or fewer silicon atoms wide. And you generate heat with every device on an (integrated circuit), so you can’t any longer carry away enough heat to make everything work, either.”

“So you need something that you can shrink smaller, if possible,” he says. “But above all, you need something that works differently than a silicon transistor, so that you can drop the power consumption, a lot.”

Typical silicon-based transistors consist of multiple terminals. Two of them – the source and drain – serve as the starting and end points for electrons flowing through a circuit. Above that channel sits another terminal, the gate. Applying voltage between the gate and source can dictate whether the electric current flows with low or high resistance, leading to either a buildup or absence of electron charges that gets encoded as a 1 or 0, respectively. But random-access memory – the form that most computer applications rely on – requires a constant supply of power just to maintain those binary states.

而不是依赖于电力charge as the basis of its approach, the researchers turned to spin – a magnetism-related property of electrons that points up or down and can be read, like electric charge can, as a 1 or 0. The researchers knew that electrons flowing through graphene, an ultra-robust material just one atom thick, can maintain their initial spin orientations for relatively long distances – an appealing property for demonstrating the potential of a spintronic-based transistor. Actually controlling the orientation of those spins, using substantially less power than a conventional transistor, was a much more challenging prospect, say the researchers.

To do so, the researchers needed to underlay the graphene with the right material, and turned to chromium oxide, a material they were familiar with from previous research. Crucially, say the researchers, chromium oxide is magneto-electric, meaning that the spins of the atoms at its surface can be flipped from up to down, or vice versa, by applying a meager amount of temporary, energy-sipping voltage.