Elected: 1972
Discipline: Physics and Astronomy
Professor Roger Arthur Cowley FRS FRSE
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Roger Cowley, who has died aged 75, was one of the leading physicists of his generation. He was a highly versatile scientist who made important contributions to the understanding of the motion of atoms in solids and liquids, the mechanisms of structural phase transitions, and to a range of magnetic phenomena. Adept at both experiment and theory, he had the rare gift of being able to see through the layers of complexity that often cloud real-world materials and capture the essence of their behaviour in simple models. Cowley’s deep intellect and analytical powers emerged early on. As a research student in Cambridge (1960-1963) he performed neutron scattering experiments to study the atomic vibrations in crystals and developed related theory. In a highly influential experiment he showed that the anomalous dielectric properties of crystals like SrTiO3 are associated with a low-frequency vibration, the so-called ‘soft-mode’, and in a seminal review he developed a method to calculate anharmonic properties such as thermal expansion and thermal conductivity using Feynman diagrammatic perturbation theory. Cowley published ten papers from his PhD work, seven as sole author.