Pressure- and Field-Tuned Spectroscopy of Strongly Spin-Lattice-Coupled Materials

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TECHNICAL ABSTRACTStrong coupling between atomic spins and the lattice in "strongly correlated" materials is associated with many scientifically important and technologically useful phenomena, including orbital ordering, multiferroic behavior, and magnetic-field- and pressure-tunable phase transitions. This individual investigator award supports a project that will involve the growth, characterization, and optical spectroscopic measurement of various single-crystal ruthenium-oxide, magnesium-oxide, and vanadium-oxide materials whose properties have highly enhanced ("colossal") responses to applied pressure and/or magnetic field, making these materials promising candidates for the next generation of "functional" materials and devices. The goal of this project is to understand the microscopic origin of these exotic and useful properties, by employing magnetic-field- and pressure-tuned optical spectroscopy to investigate the manner in which spin-lattice coupling and spin/lattice dynamics evolve through various low temperature, high-magnetic-field, and high pressure phases of these materials. Among the anticipated outcomes of this project are (i) elucidation of the microscopic origin of the colossal sensitivities these materials exhibit in response to high pressures and applied magnetic fields; (ii) insights into how to grow new materials with enhanced functional properties; and (iii) high quality single-crystal samples of correlated materials that will be made available to others in the scientific community. This project will also provide broad training to 2 graduate students in single-crystal growth and pressure- and magnetic-field-tuned optical spectroscopy, and will be used as part of an outreach program to interest K-12 students in the sciences via tours of the high field/high pressure optical laboratory. NON-TECHNICAL ABSTRACTIn many oxide-based materials, there is a particularly strong interaction between the atomic magnetic moments (which can be thought of as small bar magnets attached to the atoms) and the ordered "lattice" structure of the atoms; one important consequence of this strong interaction is that applied pressures or magnetic fields can be used to sensitively control the mobility of the electrons in, the magnetic properties of, and even the structural shape of, these materials. As a consequence, these "highly tunable" materials are promising candidates for the next generation of multi-functional switches, sensors, shape-memory structures, and other useful electronic/magnetic devices. This individual investigator award supports a project that will involve the growth of these novel oxide-based materials, and the study of the basic mechanisms responsible for their exotic properties by scattering light (i.e., "photons") from the materials while tuning the materials' properties through their novel phases found at high pressures and high magnetic fields. The goals of this project are to better understand the conditions responsible for the "highly tunable" properties of these materials (i) to elucidate how matter behaves under novel environmental conditions, and (ii) to develop new materials with enhanced functional properties. This project will also provide broad training to 2 graduate students in materials growth and state-of-the-art light scattering methods, and will be used as part of an outreach program to interest K-12 students in the sciences via tours of the high field/high pressure optical laboratory.