UC Santa Barbara

In the study of quantum materials, disorder is typically something to be avoided, since many of the quantum ground states of interest are contingent on a pristine underlying lattice. Certain forms of disorder can, however, enhance rather than obscure certain electronic or magnetic phase behaviors — pointing to engineered disorder as an additional avenue to realizing new ground states. This dissertation is concerned with both probing and controlling disorder in several families of quantum materials, using a combination of advanced scattering and synthesis techniques.First, we examine the short-range correlations of a displacive disorder mode in the kagome metal ScV6Sn6, where we unveil a frustrated Ising-like charge degree of freedom whose fluctuations likely underlie the reported pseudogap behavior above the charge ordering temperature. Second, we explore the LnCd3P3 (Ln = La, Ce, Pr, Nd) family of triangular lattice antiferromagnets, where we reveal an underlying frustrated bond instability within the unique CdP3 units. Third, we present the second-generation design of a high-pressure floating zone furnace capable of growing large-volume, high-quality single crystals. Lastly, we utilize this furnace to demonstrate the successful growth of cm3 -scale crystals of the layered perovskite Sr2IrO4 for the first time, and reveal that tuning the mixing rate of the melt allows for the growth of natively hole-doped Sr2Ir1−yO4 which exhibits a strongly modified magnetic and electronic response.