2015 Mott Medal and Prize

Professor John Saunders, Royal Holloway, University of London, for ground-breaking studies at the frontiers of ultra-low temperature physics.

Professor John Saunders

John Saunders is a pioneer in the study of helium films at ultra-low temperatures as model systems for strongly-correlated quantum matter and topological superconductivity. This has been coupled to key developments in technology: cooling techniques; noise thermometry; and nuclear magnetic resonance (NMR) using superconducting quantum interference devices.

His work is characterised by ground-breaking studies at the frontiers of ultra-low temperature physics, requiring significant technical innovation, and the investigation of model systems providing unique insights into problems of central importance and significance in condensed matter physics.

His research on two-dimensional helium has focused on atomically-layered He-3 films on graphite, which provide a unique platform for the study of Mott-Hubbard physics. Unlike electronic systems, here the interactions are short ranged. By using single layer He-3 films it was possible experimentally to verify Mott’s 1949 prediction that fermions localise under the influence of strong local interactions, observing a quantum phase transition at which the quasiparticle effective mass diverges. The frustrated magnetism of the 2D localised spin system evolves with density from quantum spin liquid to ferromagnetic. On the other hand, bilayer He-3 films exhibit tuneable heavy fermion behaviour and quantum criticality. His group has pioneered the study of topological superfluid He-3 confined in precision-engineered nanofabricated geometries, to study films of thickness comparable to the coherence length, paving the way for the study of surface and edge excitations arising from bulk-edge correspondence.

In parallel with these path-breaking discoveries, Saunders has also pushed the envelope of low-temperature physics technology. His group has designed new methods for the measurement of temperature down to sub-millikelvin scales, for the cooling of nanostructures, and has developed ultra-low temperature NMR spectrometers of spectacular sensitivity.