Both magnets and superconductors have separate technological applications, but making materials that display both properties is challenging. Professor Stephen Blundell, who carried out the ISIS muon experiments, explained that: "Superconductivity and magnetism are usually sworn enemies and refuse to cohabit in the same compound."
The most common method of making materials with both these properties has been to deposit alternating layers of compounds with each of these properties. The success of this approach is limited if the compounds have different sizes at the atomic level, leading to distortions that change the properties of each layer.
The new method forms each layer in solution and the layers are brought together by electrostatic attraction. Professor Blundell said: "Rather than build up the material atom by atom, molecule by molecule, nanosheets with different functions are self-assembled." Professor Eugenio Coronado, whose group at the University of Valencia developed the chemical technique, described this as "like constructing a building by adding entire pre-assembled floors rather than brick by brick, and is the secret behind combining these two inimical properties."
Bringing magnetic and superconducting layers together in such close proximity offers the possibility of using one property to affect the other. To examine the effect of this coupling in these new materials, ISIS muons provided a way to probe each property at a microscopic level. This allowed the volume of the sample that becomes magnetically ordered and the strength of the superconducting state to be determined.
Eugenio Coronado1, Carlos Martí-Gastaldo1, Efrén Navarro-Moratalla1, Antonio Ribera1, Stephen J. Blundell2, and Peter J. Baker2,3
1University of Valencia, 2University of Oxford, 3ISIS Facility
Research date: July 2010
This research was published in Nature Chemistry 2, 1031 (2010), "Coexistence of superconductivity and magnetism by chemical design".