Princeton University

Title: The World's Most Frustrated Magnet

Abstract: Frustrated magnets are distinguished by horrendously degenerate ground states. Nominally small perturbations - quantum or thermal fluctuations, coupling to other degrees of freedom and the like - compete to lift this degeneracy and produce a variety of phases: Neel, paramagnetic, spin liquid, spin glass, spin ice, a valence-bond solid. I will discuss recent progress in our understanding of pyrochlore antiferromagnets, fine examples of this species, with a focus on quantum "order by disorder" and a semiclassical "order by distortion" that explains many features of a peculiar spin-Peierls transition observed in several cubic spinels (cond-mat/0108505).