Power in a union: a suite of experimental techniques helps us to understand how electrons team up to overcome resistance.

A copper-oxide superconductor levitates above an array of rare-earth magnets once it is cooled below its critical temperature using liquid nitrogen.

Superconductivity, the phenomenon of zero electrical resistance and magnetic field expulsion, which occurs below a critical temperature in certain materials, has a huge potential for technological applications. Electrons in superconductors are known to join together in pairs in order to gain immunity from scattering, but exactly how this occurs in many materials has yet to be established. At present, superconducting critical temperatures are typically very low, less than 140 Kelvin (-133 Celsius), and even those materials with the highest critical temperatures have physical properties that makes them challenging to exploit on an industrial scale. A more complete understanding of the superconducting state will result in the design of superconducting materials and devices with the properties required for mass technological exploitation.

In many materials magnetism and superconductivity appear to be intimately linked. Mapping out the magnetic interactions in novel superconductors and related compounds helps us to get a handle on the environment in which electrons form superconducting pairs. The image on the left shows neutron scattering intensity maps of the magnetic excitation spectrum of a cobalt-oxide material, and is taken from Boothroyd et al. Nature, 471, 341 (2011).

We pursue an number of avenues to this end. The low temperature properties of novel superconducting materials, including copper-oxide compounds, pnictides, and organic superconductors, are investigated using high magnetic fields, neutron scattering, muon spin rotation and thermal transport techniques.

Groups working in this field