Basing the research on materials called Spin Ices, the researchers demonstrated how the “hop” of a monopole from one site in the crystal lattice of Spin Ice to the next can be attained by changing the direction of a single magnetic atom.
Although in theory, at low temperatures, the magnetic atoms do not have sufficient energy to achieve this, the team learned that as a monopole reaches a lattice site, it triggers alterations in the fields acting on the magnetic atoms surrounding it which allow them to “tunnel” through the energy barrier.
We found evidence that this mysterious low-temperature hopping is achieved through quantum tunnelling: a phenomenon that allows a quantum object to overcome an obstacle which would, according to the classical laws of physics, require more energy than the system has available to it. We showed that the magnetic atoms forming a monopole experience fields that are transverse to their own, which in turn induce the tunnelling.
Dr Quintanilla, School of Physical Sciences, University of Kent
Dr Quintanilla added, “We compute the monopole hopping rates resulting from this scenario and find them to be broadly consistent with available observations.”
The scientists state that this better insight into monopole motion in spin ice materials may facilitate future technologies based on moving magnetic monopoles, instead of electric charges.