Prof. Bumjoon Kim

Hidden orders in square-lattice iridates

Over the last decade, square-lattice iridates have received much attention as a close analog of cuprate high-temperature superconductors. Although there is not yet firm evidence for superconductivity, a remarkable range of cuprate phenomenology has been reproduced in electron- and hole-doped iridates including pseudogaps, Fermi arcs, and d-wave gaps [1]. Further, a number of symmetry breaking orders reminiscent of those decorating the cuprate phase diagram have been reported using various experimental probes. In this talk, I will  discuss our recent results from Raman spectroscopy and resonant x-ray scattering, which show clear evidence of a quantum spin nematic phase in Sr2IrO4, in which spins are quantum entangled to form a multi-polar order without breaking time-reversal symmetry. I will also briefly talk about the prospect of finding a new high-temperature superconductor in iridates using a novel growth technique that allows us to grow samples with much enhanced quality.

[1] Square-lattice iridates, Annu. Rev. Condens. Matter Phys. 10, 315-336 (2019)

Schematic of crystal growth using aerosol-assisted chemical vapor deposition