The irony of spin

Until the advent of high-temperature superconductors (based on copper), magnetism and superconductivity were considered antagonistic. Ironically, they now seem to be intimately linked.

Iron is almost synonymous with magnetism and the discovery of superconductivity for temperatures as high as 56K (-217ºC) in layered iron-arsenic compounds has lead to a dramatic increase in research into iron compounds.

We seek to understand and develop these new iron-based superconductors and related layered compounds. Fluctuating magnetic moments are key to this understanding, however the physics is complicated by complex and competing magnetic and electronic interactions.

This is a general problem in physics but these interactions can result in superconductivity and/or magnetically-induced changes in electrical resistance. Both phenomena are technologically important and current markets for each exceed one billion dollars.

The IRL team is ideally positioned to elucidate the fundamental physics of Fe-based compounds because we have made major contributions to the understanding of superconducting cuprates. This has resulted in the discovery of many new superconductors and the formation of two New Zealand start-up companies.

The research team includes physicists and chemists at IRL as well as researchers at GNS Science and at international institutions.

Crystal structures for three of the Fe-based superconductors. The different colours indicate Fe (brown), As (light green), La (purple), O (red), Ba (blue), and Se (dark green). Doping occurs for example by partially replacing O by F and Ba by K