Nonlinear and ultrafast optical investigations of correlated materials

Speaker: Hao Chu
Date & Time: Tuesday July 4, 2017 @ 3:00 - 4:00 pm
Location: AMPEL 311
Local Contact: David Jones
Intended Audience:

The spin-orbit coupled perovskite iridates Srn+1IrnO3n+1 share many similarities with the cuprate high-Tc superconductors in terms of their structural and electronic properties. For example, in single-layer Sr2IrO4, both a pseudogap as well as d-wave gap have been observed upon carrier doping. Using optical second harmonic generation rotational anisotropy (SHG-RA), I will discuss our discovery of a parity-odd multipolar order in both parent and hole-doped Sr2IrO4, which is consistent with long-standing theoretical models of symmetry broken orders underlying the pseudogap phase in the cuprates. In the bilayer Sr3Ir2O7, where no prior observations of electronic instabilities similar to those in cuprates have been reported, I will report our discovery of a charge-density-wave-like instability in electron-doped samples using pump probe optical reflectivity. This electronic instability might be fluctuating in time or spatially short-ranged. I will also demonstrate a new technique of pump probe SHG-RA, which combines the previous two capabilities and allows ultrafast photo-induced changes in point group symmetry to be measured. I will describe our on-going efforts attempting to coherently drive new magnetic states in the layered magnetic materials MPX3 (M = Mn, Fe, Ni; X = S, Se), which retain antiferromagnetism down to the ultrathin limits.