Physics Near the Mott Transition

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TECHNICAL SUMMARYThis award supports theoretical research and education on novel phenomena that occur in the vicinity of the Mott metal-insulator transition in interacting electron systems. Specific areas of interest are the physics of continuous Mott transitions, and of quantum spin liquid Mott phases that are proximate to such transitions. The emphasis will be on developing theoretical concepts in the context of either experiments on specific materials or numerical work on specific microscopic models.Specific foci of the research include: (i) new theoretical approaches to the electronic Mott transition based on insights from the better understood Mott transition of bosons,(ii) the theory of gapless quantum spin liquid phases with a focus on identifying unique experimental signatures (iii) the interplay between electronic nematic order and spin liquid physics in Mott insulators. Project (i) is an exploration of new theoretical methods to address fundamental questions concerning the fate of the electronic Fermi surface as a metal evolves into a Mott insulator. This is a key challenge in many problems in modern quantum many-body theory. Projects (ii) and (iii) are directly motivated by experiments on weak Mott insulators that find evidence for the occurrence of quantum spin liquid phases. It is expected that the work proposed will provide key insights that will be useful in interpreting the results from experiments on weakly Mott insulating materials, and would help suggest new ones. All of the projects tie in nicely with some long term research interests of the PI on developing an understanding of non-fermi liquid physics near heavy electron critical points, and in the cuprate materials.This award also supports the training of graduate students in advanced theoretical concepts and methods. The PI will involve undergraduates in the research, when possible, through the Undergraduate Research Opportunities Program at MIT. The PI will continue his efforts, begun recently, to design lectures to expose graduate students to experimental methods and the phenomenology of modern correlated materials.NONTECHNICAL SUMMARYThis award supports theoretical research and education that seeks to predict new phenomena occurring in materials that are near a special insulating state called a Mott state. Standard theoretical methods would predict that these Mott insulators are actually metallic. These methods inadequately account for the strong interactions between electrons in Mott insulators. When this is done, the metallic state gives way to an insulating state. The parent compounds of the high temperature superconductors with the highest transition temperatures are Mott insulators. Adding charges to these materials moves them from the Mott state to the high temperature superconducting state. The PI will use advanced theoretical tools to understand proposed new states of matter that occur near Mott states. The vicinity of a Mott state is thought to be a conspicuously fertile area for the discovery of new electronic states of matter and to lead to unusual electronic properties of materials that lie outside the standard textbooks. The PI also seeks to predict new phenomena near a Mott state. This is fundamental research with high risk elements. The research will advance our fundamental conceptual understanding of the electronic properties and phenomena of this class of materials. The research may also contribute to the intellectual foundations of new device technologies, particularly with increased ability to control the processing of these materials.This award also supports the training of graduate students in advanced theoretical concepts and methods. The PI will involve undergraduates in the research, when possible, through the Undergraduate Research Opportunities Program at MIT. The PI will continue his efforts, begun recently, to design lectures to expose graduate students to experimental methods and the phenomenology of modern correlated materials.