Physics of Strong Disorder and Correlation

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

NONTECHNICAL SUMMARY This award supports theoretical research and education in condensed matter physics. The theoretical work takes its inspiration from experimental discovery in new materials and aims to explain and predict novel phenomena. Such novel phenomena often arise in materials where electrons are strongly interacting with each other, and this work will focus on this rich arena. Past examples include Nobel winning discoveries such as the fractional quantum Hall effect and high temperature superconductivity. The current project involves studies of a novel state of matter called quantum spin liquid, as well as the theory behind high temperature superconductivity. This research area is particularly well suited for the training of graduate students and postdoctoral fellows because both mathematical sophistication and an understanding of real materials are required to make progress. TECHNICAL SUMMARY This award supports theoretical research and education in condensed matter physics. Strong correlation refers to physical phenomena in materials which are driven by the strong repulsive interactions between electrons. These phenomena include the origin of magnetism and a large class of insulators called Mott insulators. Recently there has been great interest in the study of a new phase of matter called the quantum spin liquid, where the tendency towards antiferromagnetic order is destroyed by quantum fluctuations. It is predicted theoretically that when this happens, novel excitations emerge which are not otherwise found in nature. Examples include fermionic particles carrying spin 1/2 but no charge and emergent gauge fields. Several candidate spin liquids have been discovered but their properties remain to be fully explored experimentally and theoretically. The project will carry out theoretical studies both to interpret existing data and to propose new experimental probes. Advances in the spin liquid problem have encouraged the P.I. to re-examine the long standing problem of high temperature superconductivity, which arises by adding carriers to a Mott insulator. The current project involves exploration of new ideas based on recent progress in the understanding of quantum spin liquids.