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CRASH-PROOF processor chips that crunch magnetic data rather than the electronic stuff could soon be on the way. Like a computer’s hard disc drive they’ll continue to store data after a power cut, but they’ll also be impervious to radiation, making them ideal for use in spacecraft.

The first step towards such a chip has been taken by Russell Cowburn and a team at the University of Durham, who have made a magnetic “NOT gate”. This is the simplest digital logic gate, which simply flips digital 1s to 0s and vice versa. Cowburn’s device exploits “spintronic” phenomena—using the fact that electrons have spin that can be aligned by a magnetic field.

He started by etching a splayed Y-shaped nanowire from a film of nickel-iron alloy. The material is ferromagnetic, which means it’s capable of becoming a permanent magnet. In a normal piece of ferromagnetic material, the spins of electrons within tiny regions or “domains” all point the same way. When the material is unmagnetised, the domains are oriented at random, but they all line up when exposed to a strong external field.

In a nanowire, however, the domains can only align themselves with the wire, and the boundary where opposite domains meet can be used to represent a digital 1 or 0, depending on whether the opposing fields meet head to head or tail to tail. The Durham team’s breakthrough has been to show that with a suitably shaped Y, it is actually possible to use an external magnetic field to switch the domain junctions from one state to the other.

Cowburn says magnetic chips using such Y-shaped NOT gates would have big advantages over electronic ones. “If the power fails, it just stops where it is,” he says. “So when the power comes on again, it just carries on from where it left off.” And because the magnetic circuits are made of metal they can work without special shielding in high-radiation environments like space, unlike traditional microchips.