Quantum Critical Phenomena and Non-Fermi-Liquid Physics

Columbia University, New York NY

Investigators

Abstract

0081075 Millis This grant supports the theoretical work of a distinguished, mid-career PI on strongly Correlated electron systems. The list of research projects in this grant includes (1) Disorder and Quantum Critical Phenomena, (2) High Temperature Superconductivity and (3) Nonequilibrium phenomena in highly correlated systems. The class of problems here is frequently referred to as non-Fermi liquid effects. They lie beyond the edge of understanding of electrons in metals offered by Landau's Fermi liquid theory. The anomalies beyond the Fermi liquid theory include the large number of thermodynamic/calorimetric results in rare-earth alloys, which are believed to be near a quantum critical point due to disorder. There are related effects in materials relevant for high-density magnetic memories and in relaxor ferroelectrics. There are nonequilibrium effects such as the high temperature resistivity of high Tc copper oxides. The projects involve analytical and numerical approaches along with close contact with relevant experimental work. %%% The theoretical work supported in this grant comes from two themes in current research on materials. There are certain anomalies in the properties of electrons in metals, which Apparently lie outside the conventional paradigm, referred to as the Landau's theory of metals. They are caused by the presence of substantial disorder and or extreme environmental such as pressure, magnetic field or temperature. The work here is fundamental and far-reaching in that it may require development of sophisticated, new mathematical tools and at the same time it is motivated by a need to understand materials which are important for high density magnetic memories or materials which use their ferroelectric properties for memory applications. This work will be carried out in close contact with experimentalists and will make use of both analytical and numerical techniques, as may be necessary. ***