Frustrated Magnetism

Frustrated magnetic systems have been studied by a large number of researchers over several decades.

More recently frustrated magnetism has received renewed interest resulting from the discovery of a class of materials know as ‘spin ice’ because of their analogy with water ice. Competing interactions in spin ice systems result in a number of interesting properties including the absence of a single minimal energy ground state.

The team at Cardiff study both bulk spin ice and artificial spin ice (ASI) analogues using a wide variety of measurement techniques in the School of Physics and Astronomy, the Wolfson Centre for Magnetics and at large scale facilities around the world.

Activities

Experiments undertaken on different forms of spin ice material have suggested that magnetic monopoles might exist within these materials, thus having profound implications for our understanding of electromagnetism and the symmetry between electricity and magnetism. As well as being of great interested to condensed matter physicist from the point of view of understanding fundamental physics spin ice materials might offer a whole host of wonderful new practical applications. In particular ASI structures may allow us to design improved magnetic data storage devices to store more information cheaply while consuming less power and failing less frequently.

In addition to other techniques measurements using muons have been carried out on bulk ‘spin ice materials’ at the STFC ISIS Neutron and Muon Source.

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Publications

• Branford, W. R. et al., 2012. Emerging chirality in artificial spin ice. Science 335 (6076), pp.1597-1600. (10.1126/science.1211379)
• Ladak, S. et al. 2010. Direct observation of magnetic monopole defects in an artificial spin-ice system [Letter]. Nature Physics 6 (5), pp.359-363. (10.1038/nphys1628)
• Bramwell, S. T. et al., 2009. Measurement of the charge and current of magnetic monopoles in spin ice [Letter]. Nature 461 (7266), pp.956-959. (10.1038/nature08500)