Magnetic monopoles imaged for first time

Posted by Emma Woollacott

Scientists have captured direct images of the long-theorized but never before seen magnetic monopoles.

Monopoles - magnets which have just a single pole - were theoretically conceived by the British-Swiss physicist Paul Dirac, who showed in the 1930s that their existence is consistent with  quantum theory.

The scientists were able to image the monopoles directly by using the highly intense x-ray radiation from the Swiss Light Source at the Paul Scherrer Institute.

"Some of the most important theories explaining how quantum matter behaves in the universe are based on their existence, but they have eluded direct imaging since they were first theoretically conceived in the 1930s," says Prof Hans-Benjamin Braun from University College Dublin.

"We have for the first time directly imaged monopoles inside an artificially created magnetic nano-metamaterial consisting of tiny magnets with a size of a couple of hundred nanometers."

As Dirac predicted, the monopoles observed by the researchers are attached to so-called 'Dirac strings', which feed magnetic flux into the magnetic monopole.

"We also directly observed how north- and south pole separate from each other in an external field, creating the Dirac string in their wake," says Dr Laura Heyderman from the Paul Scherrer Institute in Switzerland. "In addition we have now demonstrated how to control the motion of these monopoles."

When the researchers examined the way the monopoles moved, they realized that each time they increased the applied magnetic field they triggered an avalanche of magnetization reversal of adjacent islands, like a row of toppling dominoes.

The research could eventually help scientists to understand how monopoles might have interacted in the early universe.

But in the meantime, it may also have immediate applications in data transfer and storage. Working with magnetic charges rather than electrical charges could lead to big advances in power consumption and speed.

Current hard discs store data magnetically, and the next generation looks likely be built from tiny isolated magnets of the exact type investigated in this research.