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Graphene spintronics crowned latest Moore's Law extender contender

It's not just politicians and PRs who are powered by spin

Wonder material graphene could provide the basis for the future of circuitry, by using a technique known as spintronics, boffins have mused.

Spintronics uses the spin of individual electrons as the encoding method for data. This is significantly smaller than using charge, which requires thousands of electrons. Unfortunately, impurities in metal limit the size of components.

By substituting graphene for metal, Chalmers University of Technology in Sweden believes it can overcome the limitations and extend the area of a spintronics device from nanometres to millimetres. Data can be transferred from electron to electron by the magnetic effect of the spin.

Spintronics is already used in some hard drives and memory, and the University of Cambridge has investigated 3D processor design using the tech and aims to create spintronics devices by improving the purity of metals through advanced chemistry.

A team led by Professor Saroj Dash at Chalmers prefers the graphene option and is using chemical vapour deposition to create the one-atom-thin graphene wires, using deposition on to copper and then to silicon-dioxide-on-silicon wafers. This has extended the range of the spintronics to 16 micrometres and the lifetime to 1.2 nanoseconds, which Dash says is an six-fold improvement.

Professor Dash told The Register: "Basic physics says spin manipulation should be faster and less power consuming. But nobody has tested it yet in a practical device."

Dash’s colleague Dr Venkata Kamalakar Mutta told EETimes.

"My experimental set-up consists of two ferro-magnetic electrodes (one injector and one detector) placed on graphene. Other electrodes are used for completing circuits as reference electrodes and they may not be ferro-magnetic. It has two circuits, namely the current circuit and the voltage circuit. These are isolated from one another for faithful measurement of spin signal."

The short-term aim is to construct a logical component that, not unlike a transistor, is made up of graphene and magnetic materials. In the longer term things are more ambitious. Professor Dash told El Reg:

Electrons, with their spin magnetic moments aligned in one direction, can be used to store information and can be communicated over long distances as our results show. Spin magnetic moments act like memory and we can integrate memory and processor in a single device in future. ITRS is projecting spin logic and memory technology. This is called All Spin Logic.

He wouldn't be drawn on what processors which used the technology might be like, saying only: "Our results are basic research. Engineers are thinking about All Spin Logic devices on graphene."

The university stated: "Whether spintronics can eventually fully replace semiconductor technology is an open question, a lot of research remains. But graphene, with its excellent spin conduction abilities, is highly likely to feature in this context." ®

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