Condensed Matter Theory Seminar | October 23, 14:00
Optical Probes and Light-Induced Chargon Condensation in a Quantum Spin Liquid
Quantum spin liquids are exotic states of matter characterized by fractionalized excitations and emergent gauge fields. Identifying experimental signatures of these excitations and understanding how they respond to external driving remain central challenges in condensed matter physics.
In this talk, I will discuss the equilibrium and nonequilibrium optical properties of the organic Mott insulator κ-(BEDT-TTF)₂Cu₂(CN)₃, a candidate quantum spin liquid. I will first show how the molecular structure of this material allows spin excitations to couple to electromagnetic radiation, providing a possible explanation for the continuum of in-gap optical absorption observed experimentally.
I will then turn to recent pump-probe experiments reporting a transient superconducting-like optical response. Using a fractionalized description of the electronic degrees of freedom, I will show how periodic modulation of the chargon gap can parametrically enhance charge fluctuations and produce an inductive optical response. Finally, I will discuss how light-induced chargon condensation can give rise to unconventional dynamical states, including charge-density waves and pair-density waves.
MPI-FKF
0.03
Contact: Urban Seifert