Physics of Strong Disorder and Correlation

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

TECHNICAL SUMMARY This award supports theoretical work on the physics of strongly correlated electronic systems. It is known that many important phenomena in materials science originate from the strong repulsion between electrons in solids. These include all of magnetism, metal-insulator transitions and, more recently, superconductivity. A particularly exciting recent development is the discovery of materials which are candidates for the long sought quantum spin liquid. In these systems the electrons are localized by correlation but their spins do not form an ordered state down to the lowest temperature due to quantum fluctuations. Past theoretical work has predicted that many novel phenomena may emerge at low temperatures, such as specific heat and thermal conductivity which behave like metals in these materials which are charge insulators. These predictions have recently been observed experimentally. The plan is to build on the past success to achieve a deeper understanding of this novel phenomenon. Theory will be developed which aims to explain in detail the experimental observations and to predict new ones. It is possible that an understanding of the quantum spin liquid will pave the way towards an understanding of the high temperature superconductors, especially in the under doped region, where the formation of quantum spin liquids may be the driving force behind the many anomalous properties observed there. Theoretical work on the high temperature superconductors will be pursued armed with new insights gained from the studies of quantum spin liquids. Progress on these long standing problems represent a new paradigm and will have strong impact on condensed matter physics and materials science. NONTECHNICAL SUMMARY This award supports theoretical research and education in condensed matter physics. The theoretical work takes it 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. 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.