Controlling THz Light-Matter Coupling to Manipulate Layered Quantum Materials
Dr. Alexander von Hoegen
Feodor Lynen Postdoctoral Research Fellow
MIT
I will discuss how terahertz (THz) light-matter coupling can be controlled in both time and space to transiently manipulate the properties of layered quantum materials. In this context, THz-driven collective modes provide a powerful route to reveal and dynamically shape the interplay between microscopic degrees of freedom. I will illustrate this by focusing on a quasi-two-dimensional magnetic material, where THz excitation uncovers hybrid magnon-phonon modes and stabilizes a new metastable magnetic ground state. This emergent phase arises from a unique interplay of magnetic fluctuations and strong spin-lattice coupling.
In the second part, I will show how THz light-matter interactions can be custom-tailored by engineering a sample’s geometry and dielectric environment. This gives rise to distinctive resonances that confine electromagnetic waves to deeply sub-wavelength scales. By directly visualizing the THz electrodynamics in the layered superconductor Bi 2 Sr 2 CaCu 2 O 8 , I will demonstrate a crossover from geometry-dominated behavior at low temperatures to a scattering-dominated regime above the transition temperature. Together, these findings highlight the versatility of THz-driven approaches to control and probe emergent phenomena in layered quantum materials.