Speaker: Rick Averitt (UC San Diego)

Title: Investigating order parameter dynamics and control in quantum materials using terahertz spectroscopy

Abstract: Dynamics and control of quantum materials using light has emerged as a frontier research area.  There are numerous possibilities to investigate including photoinduced metastability, creating non-equilibrium states with emergent properties, or impulsively driving an order parameter to investigate the nonlinear “optical” response which can encode properties not evident with linear optical probes. Terahertz spectroscopy is a particularly useful probe of low energy electrodynamics in quantum materials in both the static and dynamic limits. Following a brief introduction to this area of research, I will present concrete examples from my research group. This includes: (i) Gentle photoexcitation of La2-xBaxCuO4 resulting in a collapse of charge order with the development of incipient superconducting signatures above the equilibrium superconducting transition temperature. (ii) Gentle photoexcitation of the putative excitonic insulator Ta2NiSe5 resulting in stimulated nonlinear parametric generation that serves as a reporter of the excitonic condensate and its coupling to phonons.

Short Bio: Richard Averitt received his PhD degree in Applied Physics from Rice University in 1998 for work on the synthesis and optical characterization of gold nanoshells. Following this, Richard was a Los Alamos National Laboratory Director’s Postdoctoral Fellow where his work focused on time resolved far-infrared spectroscopy of strongly correlated electron materials. In 2001, Richard became a member of the technical staff at Los Alamos, and in 2005 a member of the Center for Integrated Nanotechnologies co-located at Los Alamos and Sandia National Laboratories. In 2007, Richard joined Boston University as a faculty member in the Department of Physics and the Boston University Photonics Center. Since 2014, Richard has been with the Department of Physics at UC San Diego. Richard’s research is primarily directed towards characterizing, creating, and controlling the optical and electronic properties of quantum materials. This includes transition metal oxides and metamaterials.