Magnetricity: understanding and exploiting a new phenomenon

Lead Research Organisation: University College London
Department Name: London Centre for Nanotechnology

Abstract

While electric charge currents (electricity) have dominated much of the agenda of pure and applied physics for more than a century, the analogous magnetic phenomenon has never been investigated, either experimentally or theoretically. The reason is that magnetic charge currents were thought not to exist. However all this has changed after a series of recent developments that have demonstrated the existence of magnetic charges in a type of material called `spin ice'. This material contains emergent magnetic charges or monopoles that may flow to form a magnetic equivalent of electricity or magnetricity . The magnetic charges of spin ice are not elementary particles, so cannot escape the material, but they do behave like magnetic charges in a practical sense. This type of magnetic charge is common to all magnetic materials, but it is only in spin ice that it exists in the form of nearly point-like quasiparticles (monopoles) that are free to conduct magnetic current. The magnetic monopoles of spin ice are the most vivid example of an emergent excitation in condensed matter yet discovered, and have the added attractive quality that they directly couple to the magnetic field. They are thus of interest not only at the level of basic physics, but also for potential applications ( magnetronics ). Of course this is a long way off but a proof of principle would illuminate the exciting possibilities. The main aims of the project are to understand the basic physics of magnetricity with a view to controlling the magnetic current, observing charge rearrangements and, ultimately, building a device. In order to do this we will focus on understanding the basic properties of magnetic charge transport in spin ice in both its bulk form and in the form of thin films. We will also explore thermalised artificial spin ice arrays.

Planned Impact

Important results of this work will be published in high impact journals like Nature, Science and Physical Review Letters as well as more technical journals such as Physical Review B and Journal of Physics-Condensed Matter. In the event of a high impact paper, the result will be advertised by press releases organised by the LCN and UCL. Two post doctoral workers will gain invaluable skill and networking opportunities by interacting with a group of collaborators at the forefront of a topical area of science. Three Ph. D. students will be technically trained in the areas of condensed matter physics, nanoscience and solid state chemistry, and will gain experience at collaboration and team-working. Judging by the enormous level of public interest already shown in magnetricity , it seems likely that this study will contribute to general public awareness and understanding of science. The work will be communicated to a scientific audience via lectures at international conferences, such as the series of highly frustrated magnetism (HFM) conferences that take place every two years or so. It will also be communicated to the general public at science festivals such as the Cheltenham Science Festival. In the event that this research leads to commercially exploitable results, UCL and the LCN has well established mechanisms in place to exploit the results and retain intellectual property. Spin ice led to three front covers of Nature/Science and many articles in these journals. The public awareness of recent work on magnetricity and magnetic monopoles has been enormous, via newspaper articles, webpages etc.

Publications

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Bovo L (2013) Determination of the entropy via measurement of the magnetization: application to the spin ice Dy2Ti2O7. in Journal of physics. Condensed matter : an Institute of Physics journal

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Bovo L (2014) Restoration of the third law in spin ice thin films. in Nature communications

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Bovo L (2014) Restoration of the third law in spin ice thin films. in Nature communications

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Bovo L (2013) Crystal shape-dependent magnetic susceptibility and Curie law crossover in the spin ices Dy2Ti2O7 and Ho2Ti2O7. in Journal of physics. Condensed matter : an Institute of Physics journal

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Kaiser V (2013) Onsager's Wien effect on a lattice. in Nature materials

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Paulsen C (2014) Far-from-equilibrium monopole dynamics in spin ice in Nature Physics

 
Description Developed the science of magnetic currents and the first thin films of spin ice.
Exploitation Route Opening up these fields provides new opportunities for studying magnetic phenomena.
Sectors Other