Effects of spin-orbit interactions in condensed matter are an important and rapidly evolving topic. Strong competition between spin-orbit, on-site Coulomb and crystalline electric field interactions in iridates drives exotic quantum states that are unique to this group of materials. This colloquium offers a brief review of current experimental studies of iridates  and emphasize discrepancies between experimental confirmation and theoretical proposals that address superconducting, topological and quantum spin liquid phases. It then reports our most recent study on electrical-current controlled behavior in iridates . Electrical control of structural and physical properties is a long-sought, but elusive goal of contemporary science and technology. This work demonstrates that a combination of strong spin-orbit interactions and a canted antiferromagnetic Mott state is sufficient to attain that goal and points the way to novel possibilities for functional materials and devices .
Gang Cao obtained his PhD from Temple University under direction of Prof. Jack E. Crow in 1993. Dr. Cao subsequently worked at the National High Magnetic Field Laboratory from 1993 to 2002, and then University of Kentucky from 2002 to 2016 before he joined the faculty of the University of Colorado at Boulder. Dr. Cao is Fellow of the American Physical Society. His research encompasses a methodical search for novel quantum materials in the single-crystal form, and a systematic effort to elucidate the underlying physics of these materials. Visit his homepage for details: https://www.colorado.edu/lab/cao/
1. “The Challenge of Spin-Orbit-Tuned Ground-States in the Iridates: A Key Issues Review”, Gang Cao and P. Schlottmann, Reports on Progress in Physics 81 042502 (2018); https://doi.org/10.1088/1361-6633/aaa979
2. “Electrical Control of Structural and Physical Properties via Spin-Orbit Interactions in Sr2IrO4”, G. Cao, J. Terzic, H. D. Zhao, H. Zheng, Peter Riseborough, L. E. DeLong, Phys. Rev. Lett. 120, 017201 (2018); https://doi.org/10.1103/PhysRevLett.120.017201; Editor’s Suggestion