Moving monopoles detected

Researchers have detected movement of magnetic monopoles at room termperature in an assembly of nanomagnets.
Researchers have detected movement of magnetic monopoles at room termperature in an assembly of nanomagnets.
Research
(28/10/2010)

The search for magnetic monopoles - isolated magnetic charges that can move freely, similarly to electrical charges - has long been considered one of the principal challenges of modern physics in the field of electromagnetism. A study published in Nature Physics reports the detection of moving monopoles at room temperature in an assembly of nanomagnets, in research carrired out by a team including Arantxa Fraile Rodríguez from the UB's Department of Fundamental Physics, who took part in the project during a  temporary stay at the Paul Scherrer Institut (Suiza).

Researchers have detected movement of magnetic monopoles at room termperature in an assembly of nanomagnets.
Researchers have detected movement of magnetic monopoles at room termperature in an assembly of nanomagnets.
Research
28/10/2010

The search for magnetic monopoles - isolated magnetic charges that can move freely, similarly to electrical charges - has long been considered one of the principal challenges of modern physics in the field of electromagnetism. A study published in Nature Physics reports the detection of moving monopoles at room temperature in an assembly of nanomagnets, in research carrired out by a team including Arantxa Fraile Rodríguez from the UB's Department of Fundamental Physics, who took part in the project during a  temporary stay at the Paul Scherrer Institut (Suiza).

Magnetic poles always appear in pairs, meaning that a magnet is an elementary component with both a north and a south pole. Therefore, dividing a magnet in two does not divide the poles themselves but in fact creates two new magnets, each of which will have its own north and south poles. In 1931, the physicist Paul Dirac concluded that these monopole pairs can be separated provided that a connection is maintained between them that transports the magnetic flux, which became known as the "Dirac String".

"In our study we were able to generate monopoles in an artificial assembly of nanomagnets and observe their movement at room temperature. When we inverted the magnetization we found that two oppositely-charged monopoles remained connected by a one-dimensional line of magnets, where the north pole of each magnet is next to the south pole of its neighbour, and so form the Dirac string", explains Fraile. 

Until now there was no reproducible experimental evidence of the existence of monopoles in elementary form, but recent studies in this field have harnessed the experimental potential for generating magnetic monopoles that emerge as effective manifestations in complex collective systems in a structure described as "artificial spin ice", due to the  similarity between the distribution of the ferromagnetic islands of which they are formed and the structure of water ice.
 
Elena Mengotti, Laura J. Heyderman, Arantxa Fraile Rodríguez, Frithjof Nolting, Remo V. Hügli, Hans-Benjamin Braun. "Real-space observation of emergent magnetic monopoles and associated Dirac strings in artificial kagome spin ice". Nature Physics. DOI: 10.1038/NPHYS1794 (2010).