Joint VINSE & Physics Colloquium Series: “Fundamental Excitations in Solids” Dr. Xiaoqin Elaine Li; UT Austin 1/19/17
Thursday January 19, 2017
Xiaoqin Elaine Li
UT Austin
Associate Professor of Physics
Title: “Fundamental Excitations in Solids”
4:00 PM, 4327 Stevenson Center
Refreshments served at 3:30 PM in 6333 Stevenson Center
Abstract
Fundamental excitations (e.g. plasmons, excitons, phonons and magnons) determine both the equilibrium and non-equilibrium properties of solids such as metals, semiconductors, and magnetic materials. In this talk, I will give a few examples of our recent work on investigating how such fundamental excitations and particularly coupling between different types of excitations can be probed and controlled. In one example, we develop a temperature sensing method capable of characterizing phonons and magnons temperatures separately. Using such a temperature sensor, we demonstrate that magnons and phonons in a magnetic insulator can be driven out of local equilibrium. This experiment provides quantitative information on phonon-magnon coupling strength, which is essential to a host of newly discovered phenomena in the emerging field of spin caloritronics. In another example, we observe that the scattering spectrum of a plasmonic nanoparticle is modified by a single semiconductor quantum dot even though their scattering cross sections differ by four orders of magnitude. The coupling between the classical plamonic resonance and the exciton resonance (a true quantum two-level system) is manifested as a Fano resonance mediated by single photon absorption and scattering.