CAREER: Probing an Emergent New Class of Electronic Liquid Crystals Using Synchrotron X-rays: Superconductors and Beyond

Boston College, Chestnut Hill MA

Investigators

Abstract

Nontechnical Abstract: New materials, from semiconductors to plastics, have revolutionized our lives. Liquid crystals, for example, have transformed the way that we display and transmit information. However, these advances occurred only after we had developed an understanding of the properties of these materials, which share the properties of both liquid and solids, and the complex phases (arrangements of molecules) that they exhibit. Recently, the ideas that underlie our understanding of liquid crystals are being applied to understand the electronic properties of new materials such as high temperature superconductors. A more detailed understanding of the properties of these materials will allow them to be optimized for applications such as power transmission and energy storage. Under this CAREER award the PI and his students will apply a unique combination of advanced x-ray techniques to study systems such as high-temperature superconductors and charge density wave materials with an ultimate goal of establishing a new understanding of these unique phases of quantum matter. Integrated into the research is a plan for education and outreach centering around two key research components-advanced x-ray facilities and superconductors. The former is provided through K-12 mentoring, undergraduate and graduate training at x-ray facilities and Boston College, course development, and outreach presentations for minority faculty. An outreach plan focused on superconductors is planned that features both lectures and maglev demonstrations to be given to the general public through participation in two programs run by the MIT Museum, to the students of regional middle and high schools through school visits, and to their teachers through organizing small training workshops. Technical Abstract: A central theme of condensed matter physics is to discover and understand the emergence of novel phases of quantum matter. Research in the past decade has brought a number of such phases to the limelight, including electronic liquid crystal phases. These quantum phases were literally proposed in analogy to the liquid crystalline phases of classical fluids in terms of their similarities in the patterns of broken symmetry. Two classes of electronic liquid crystalline phases, the electron nematics and smectics, have been primarily focused on and attracted significant interest. Here, the research team seeks a further generalization of that fascinating analogy through the incorporation of the third known major liquid crystalline phase--the cholesterics that breaks long-range chiral symmetry. Initial indications for the possible existence of electron cholesterics in a transition-metal dichalcogenide and some high-Tc superconductors have recently been found experimentally, showing its potential of being as prevalent as its nematic and smectic counterparts in quantum matter. In order to look into this intriguing possibility, the principal investigator proposes a comprehensive experimental survey in this emerging frontier with the aid of a unique combination of synchrotron x-ray techniques. These techniques are element specific and can directly probe electronic states via different physics processes on different chirality-related physical quantities. Their joint force allows the existing candidate phases to be scrutinized to previously unattainable depth, and lays a foundation for future explorations on other condensed matter systems. Specifically, the proposed studies of cuprate superconductors aim for a unified understanding based on a unique chiral perspective of charge ordering phenomena - a current focus of the high-Tc field.