Upcoming Events

The revolutionary impact of graphene and single layer transition-metal dichalcogenides on solid-state
physics has led to a quest for materials with novel optical, electronic and magnetic properties. As a result of
this process, more and more van der Waals materials characterized by a collective behavior of their electronic
constituents have made an appearance on the center of the stage of solid-state research. So far, these
quantum materials encompass correlated insulators, topological insulators, and superconductors, as well
as a fascinatingly broad palette of ferroelectric, multiferroic, and magnetic crystals.
Optical spectroscopy studies of these materials recently discovered excitons that are deeply intertwined
with a collective quantum state. With properties that have no analog amongst excitons in conventional
band semiconductors, these excitons not only inherit a tremendous potential for the design of novel
optoelectronic devices, but also represent an exciting material platform to uncover new facets of light-matter
interactions. In this talk, I will introduce two different types of van der Waals antiferromagnetic crystals
reported to date to host such strongly correlated excitons: the correlated insulator NiPS3 and the magnetic
semiconductor CrSBr.
I will then focus on our recent study on strong light-matter coupling in NiPS3, a magnetic crystal
with antiferromagnetic zig-zag spin ordering below the Néel temperature. In this material, a previously unobserved
class of polaritonic quasiparticles emerges from the strong coupling between its spin-correlated
excitons and the photons inside a microcavity. I will show how hybridization with light offers unique opportunities
to study the nature of novel magnetically coupled excitations in antiferromagnetic insulators and
present our microscopic understanding of these spin-correlated excitons. By establishing strong coupling
between photons and correlated optical excitations in a magnetic crystal, our work introduces van der Waals
quantum materials to the field of strong light-matter physics and provides a path towards the design and
control of correlated quantum states via cavity quantum electrodynamics.