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A group of international researchers at the Helmholtz-Zentrum Berlin (HZB) have observed magnetic monopoles and how they emerge in a real material for the first time.

Magnetic monopoles are hypothetical particles that carry a single magnetic pole. In the material world, this is quite exceptional as magnetic particles are usually observed as dipoles - north and south combined. However, in 1931 the physicist Paul Dirac theorized that magnetic monopoles can exist at the end of tubes or "strings". Researchers had long tried to prove the existence of these Dirac strings - to no avail until now.

In a neutron scattering experiment, Jonathan Morris, Alan Tennant and colleagues at the HZB investigated a single crystal of dysprosium titanate which crystallizes in a remarkable geometric form called a pyrochlore lattice. When placed in a magnetic field at temperatures between 0.6 and 2 Kelvin, the lattice reorganized itself into Dirac strings, or "spin spaghetti", with visible magnetic monopoles at their ends.

These findings prove that monopoles exist as emergent states of matter, i.e., they emerge from special arrangements of dipoles and are completely different from the constituents of the material. "We are writing about new, fundamental properties of matter," says Jonathan Morris, "these properties are generally valid for materials with the same topology. This can have major implications for the development of new technologies."

More information: http://www.helmholtz-berlin.de/aktuell/pr/pm/index_en.html