School of Physics Colloquium

Abstract: Effects of spin-orbit interactions in condensed matter are an important and rapidly evolving topic. A sea change occurred with the discovery of spin-orbit interactions in graphene by Mele and Kane, which has led to the exciting new field of physics addressing a rare interplay between spin-orbit and Coulomb interactions in condensed matter. I will describe an entirely new hierarchy of energy scales inherent in 4d- and 5d-electron based oxides and its unique consequences, highlighting discrepancies between experimental confirmation and theoretical proposals that address superconducting, topological and quantum spin liquid phases in iridates.

I will then present our recent discoveries of novel quantum phenomena in iridates and ruthenates and conclude by venturing a perspective for research on spin-orbit-coupled oxides [1,2].

References: 1. Physics of Spin-Orbit-Coupled Oxides, Gang Cao and Lance E. De Long, Oxford University Press; Oxford, 2021 2. The Challenge of Spin-Orbit-Tuned Ground States in Iridates: A Key Issues Review, Gang Cao and Pedro Schlottmann, Reports on Progress in Physics, 81 042502 (2018)

Bio: Gang Cao is professor of physics at University of Colorado at Boulder. Prior to the current appointment, he was Jack and Linda Gill Eminent Professor at University of Kentucky, and staff scientist at National High Magnetic Field Laboratory, respectively. He received his Ph.D. in Physics under direction of Prof. Jack E. Crow at Temple University in Philadelphia in 1993. His research interests focus on discovery, synthesis, and study of 4d and 5d transition metal materials and high-field, high-pressure and low-temperature properties of these materials. Prof. Cao was elected Fellow of the American Physical Society (DCMP) in 2009.