Phonons, Lattice Instabilities and Superconductivity

Abstract

The relationship of phonon anomalies and lattice instabilities to high Tc superconductivity is explored. Inelastic neutron scattering studies have revealed an intimate and dramatic relation between certain phonons and lattice transformations, real or incipient, for moderate to high Tc superconductors, which are minimal or nonexistent in very low Tc or nonsuperconductors. Experimentalevidence is presented for a wide variety of superconducting materials and possible theoretical explanations for their behaviour are discussed.