# 2008 Rayleigh medal and prize

Professor John Chalker

*University of Oxford*

*For important original and innovative contributions to solid-state physics, particularly in the area of exotic quantum phenomena.*

The **Rayleigh medal and prize** for distinguished research in theoretical, mathematical or computational physics has been awarded to **Professor John T Chalker**, Professor of Physics in the Rudolf Peierls Centre for Theoretical Physics at the University of Oxford, for important original and innovative contributions to solid-state physics, particularly in the area of exotic quantum phenomena.

Professor Chalker has played an outstanding role in advancing our understanding of an intriguing phenomenon - the quantum Hall effect. This is the quantum version of the classical Hall effect (in which electrons are deflected to one side of a conductor by passing a current at right angles to a magnetic field). In two-dimensional electron systems, in strong magnetic fields at low temperatures, the Hall resistance varies in a stepwise, quantum fashion. The effect now provides a very precise standard for electrical resistance.

Chalker’s studies laid the theoretical foundation for new research directions in quantum Hall systems. He invented the network model which captures the essence of quantum Hall transitions in a simple way that could be extended to other condensed-matter phenomena. He also elucidated what happens at the crossover point between two and three- dimensional systems, pointing out that stacks of 2D systems would generate a chiral metal with circulating charges at the surface. He also predicted the existence of rather peculiar quantum Hall charge-density wave states. Their subsequent discovery caused quite a stir amongst colleagues.

Chalker has also worked on disordered conductors and on systems showing cooperative electronic behaviour, such as antiferromagnetism featuring competing interactions.

Professor Chalker is one of the leading condensed-matter theorists of his generation. He blends a full mastery of elaborate mathematical formalism with keen physical intuition, able to ‘see’ the physics behind equations; he is a deep thinker and true explorer of physics.