Novel Physical Phenomena in Single-Crystal Oxides

The proposed research encompasses a systematic effort to elucidate the underlying physics of spin-orbit-driven novel phenomena recently uncovered and a rigorous search for new spin-orbital materials having exotic ground states. Intellectual Merits: Condensed matter and materials physics addresses identification of novel, fundamental properties of solids and liquids that have generated a remarkable number of cutting-edge technologies in recent decades. It is widely recognized that whoever discovers and controls the optimized synthesis of novel materials generally controls the investigation of their often unique properties and, ultimately, their successful integration into advanced technologies. Emerging technologies increasingly rely upon high quality, bulk single crystals and epitaxial thin films to underpin both definitive studies of fundamental properties, and optimal inclusion in state-of-art device structures. Unfortunately, U.S. leadership in materials research has seriously eroded in recent years due to a growing shortage of scientists and engineers who possess skills in both the synthesis and characterization of new materials. The current situation presents an urgent national challenge that could ultimately undermine our economic competitiveness if left unaddressed. Building upon our recent successes, the proposed research will continue to emphasize synthesis and characterization of novel transition metal oxides in bulk-single-crystal form. Our pioneering research on single crystals of iridates, ruthenates and related systems has already revealed a wide array of phenomena seldom or never found in other materials and helped initiate a rapidly growing field of the iridates and ruthenates. It is now recognized that spin-orbit interactions (SOI) vigorously competes with Coulomb interactions, non-cubic crystal electric field and Hund's rule coupling, and critically biases their mutual competition to stabilize ground states with exotic behavior, which sharply contrasts with traditional electronic structure arguments. The most profound effect of the SOI is the Jeff=1/2 insulating state [1*, 2*], a new quantum state that represents the novel physics in the 5d-based systems. A great deal of recent experimental and theoretical work has appeared in response to this new quantum state discovered by the PI and collaborators [1*, 2*], which has presented us new physics and profound challenges. It is the new physics and challenges we seek to further pursue. It deserves to stress that one of PI's proven strengths is the unique capability to develop and synthesize a wide range of novel single-crystal oxides, which is essential to the success of a comprehensive program for materials research such as this one. Broader Impact: The proposed program provides all students involved rigorous training that emphasizes both synthesis and characterization techniques covering a broad spectrum of materials and experimental probes. The comprehensive facilities in PI's lab allow these activities to be done under the same roof so that the students can acquire hands-on experience in specialized investigations of structural and physical properties of materials. They will also be trained via short courses, seminars, national lab visits, paper and proposal writing, and conference participation. The transfer of technical expertise will be achieved via direct integration of the students into ongoing research efforts with a goal of professional journal publication of results. The proposed program will also constitute a key thrust within the Center for Advanced Materials (funded by NSF EPSCoR RII) where the PI is Director. This association will help nurture interdisciplinary expertise that will generate synergies and attract new students who are the future human capital in technologies driving the economy.