CAREER: High Pressure Studies of Novel Quantum Phase Transitions

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*** Non- Technical Abstract ***When matter is tuned from one phase to another (e.g. magnetic to non-magnetic, or insulating to metallic) unexpected phases often emerge near the transition. Studies of systems exhibiting such transitions (known as "quantum phase transitions") not only have the potential to advance our understanding of matter on a basic level, but also to provide insights that may allow us to tailor these emergent quantum phases for practical applications. One example of such an emergent phase is superconductivity. Superconductors exhibit completely lossless transmission of electricity, and advances in superconducting materials have the potential for broad impacts with applications including low-loss power lines, high efficiency energy storage units, electrical generators and motors, sensitive magnetic field detectors, high frequency filters, magnetically levitated trains, and computers. The goal of this project is to use applied high pressure to discover new emergent phases of matter and to advance our ability to understand and control these phases. Applied pressure provides a powerful means of rapidly tuning a single material through a variety of phases. Through an integrated outreach program, K-12 students from groups under-represented in STEM (Science, Technology, Engineering, and Mathematics) will learn that science can be exciting and that they can have fun learning physics principles. This positive experience will encourage some of these students to pursue STEM educations and careers. Undergraduate and graduate students will learn to become better scientific communicators through their outreach participation and will receive interdisciplinary technical training in the laboratory.*** Technical Abstract ***The study of phase transitions that are driven by quantum, rather than thermal, fluctuations represent one of the frontiers of condensed matter physics. Such systems show a strong propensity to exhibit intriguing and poorly understood phenomena associated with the interplay between competing quantum ground states. By affording comparison with theory over a continuous range of conditions, experiments designed to drive materials through quantum phase transitions using hydrostatic pressure render a potent contribution to advancing our understanding of the exotic phases of matter that sometimes emerge near such transitions. The goal of this project is to carry out high pressure experiments designed to advance our understanding of the properties of matter in the vicinity of quantum phase transitions. A particular emphasis is placed on the emergence of novel superconducting states. The approach can be broadly summarized as follows: (1) Synthesize high-quality, single-crystalline specimens of materials that are either known to or likely to exhibit quantum phase transitions, (2) Probe the properties of these materials under multi-extreme conditions of high-pressure, high magnetic fields, and low temperatures, and (3) Further refine certain high pressure techniques so that they are simple enough to perform as a routine part of sample characterization.