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New spintronics material in town – it's antiferromagnetic

A team of international researchers from the University of Nottingham has found a new material – copper manganese arsenide – which could be the future of computer storage, according to a study published in Science.

Using a semiconductor as a template, a thin film of CuMnAs(copper manganese arsenide) crystals was grown on the base to create a storage device that held a single bit, according to the study "Electrical switching of an antiferromagnet".

Magnetic memory traditionally uses ferromagnetic materials to encode the 1s and 0s.

But as the paper's authors point out: "A weakness of this approach — that strong magnetic fields can erase the encoded information — could be avoided by using antiferromagnets instead of ferromagnets. But manipulating the magnetic ordering of antiferromagnets is tricky."

Copper manganese arsenide is an antiferromagnet. The spin of the electrons creates a regular pattern where neighbouring electrons' spins point in opposite directions, making the material not susceptible to external magnetic fields.

When the crystal is zapped with electric currents, the electron spins rotate in the same direction, creating a new arrangement which encodes information. This arrangement remains intact even when the power is turned off, making it effective for storing data.

The position of the electron spins is revealed by applying another pulse of current, allowing the information to be read.

Dr Peter Wadley, lead author of the paper, said: “We use an electric current to write, that is turn, a bit and then a smaller current to read it."

Wadley already has a working USB prototype of the device sitting on his desk. “To compete with commercial storage devices – it'll take years before it can be used as the memory needed is quite high,” but it's “already a lot closer than I'd thought it'd be at this stage”, he told The Register.

Storing memory by spintronics has many potential advantages over current commercial data storage devices. More information can be held as the memory units can be packed closer together and advocates of that technology say it is more stable than non-volatile memory such as flash.

It is also thought that antiferromagnetic storage devices could also be up to 1,000 times faster than current storage devices, although this is yet to be proven. ®




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