****NON-TECHNICAL ABSTRACT**** Cooled to sufficiently low temperatures matter generally takes on a solid crystalline form. In rare cases however, fluctuations normally only found at higher temperatures can persist to the absolute zero temperature. Such materials present profound scientific challenges and they have unusual responses to external stimuli which are of interest for applications. This project seeks to understand and control strongly fluctuating matter by subjecting it to extreme conditions of pressure, stress, magnetic fields, and electric fields. Extreme conditions drive such materials between strongly fluctuating and conventional crystalline phases thus exposing mechanisms behind the anomalous properties. The materials will be probed by neutron scattering, a technique that provides detailed information about atomic scale structure and motion. The experiments will be carried out on materials that contain strings or planes of interacting magnetic ions that do not form crystalline magnetic states under ambient conditions. Some of the materials respond magnetically to electric fields and vise versa. High electric field experiments will seek a comprehensive understanding of this phenomenon, thereby leading to the ability to optimize materials for applications. The project will teach graduate students to use neutron scattering for condensed matter physics and attract young students to science through collaboration with a talent development high school.
Materials governed by dynamic correlations present profound scientific challenges and opportunities for applications. This project seeks insights about such correlated matter through experiments on topical materials under extreme thermodynamic conditions. Quasi-two-dimensional magnets with competing interactions can remain in a dynamic correlated state at temperatures much less than the energy associated with the two particle interactions. Neutron scattering experiments under high uniaxial stress will be used to explore different low temperature phases of such systems. High pressure will be used to probe the quantum phase transition to long-range order from one- and two-dimensional quantum paramagnetic phases. Highly magnetized states of various quantum paramagnets will be probed in search of a field induced mixed phase analogous to that of type II superconductors. To understand and optimize multiferroic materials for applications, polarized neutrons will be used to explore the effects of high electric fields on the magnetic structure. The project will provide graduate education in the use of neutron scattering for condensed matter physics and seeks to attract more young people to science through collaboration with a talent development high school.
