Dr. Anshul Kogar, MIT

“Light-Matter Interaction in Charge Density Waves”

Abstract: When electrons in a solid are excited with light, they can alter the free energy landscape and access regions that are beyond reach in thermal equilibrium. In this talk, I will discuss a few of our recent ultrafast electron diffraction results on charge density wave (CDW) materials showing that, under far-from-equilibrium conditions, we observe strong evidence for topological defects. These defects are crucial in explaining how the amplitude of the CDW recovers well before longrange phase coherence. I will also show that in certain CDW materials, these defects can be manipulated with light to form metastable structures. Lastly, I will show that light can be used to unleash a CDW that is not present in equilibrium.