One of the early posts I made here concerned the search for magnetic monopoles. Ordinary magnets all have two poles, conventionally labeled North and South; unlike poles attract each other, like poles repel each other. If you chop a magnet in two, each piece has two poles. In the classical theory of electricity and magnetism, summarized in Maxwell’s Equations, it is possible to have a free positive or negative electric charge, but the existence of a free North or South pole is ruled out.
The physicist Paul Dirac proposed, in a 1931 paper [PDF here], that magnetic monopoles could exist, and that if they did, it would explain the quantization of electric charge. Ever since, physicists have been looking for evidence to confirm the existence of such monopoles. Last fall, the first detection of monopoles was reported, in a neutron-scattering experiment on a crystal of dysprosium titanate at temperatures of less than 2.0 K.
The PhysOrg.com site now has a report that a team of scientists, working at the Paul Scherrer Institute in Switzerland, have captured an image of emerging magnetic monopoles in a magnetic material.
“We have for the first time directly imaged emergent monopoles inside an artificially created magnetic nano-metamaterial consisting of tiny magnets with a size of a couple of hundred nanometers,” explains Professor Braun.
(Professor Hans-Benjamin Braun, from the School of Physics at University College, Dublin, was co-leader of the experimental team.) The images were made using very high-energy X-rays from the Swiss Light Source at the Paul Scherrer Institute. The results vindicate Dirac’s predictions about how monopoles emerge; they are attached to Dirac strings, which act to channel magnetic charge. The research paper [abstract] has been published in the journal Nature Physics.
In addition to capturing these images, this work is noteworthy because, unlike the earlier experimenters, the researchers were able to produce the emergent monopoles at room temperature. This might in time pave the way for the use of magnetic charge [= monopoles] for information technology products, which at present use electric charge for data storage. Using magnetic charge might lead to significantly reduced power consumption and increased storage density. Of course, there is a great deal more work to do before this shows up in real products, but it is another example of how quantum mechanics can make surprising and counter-intuitive predictions that turn out to be true.