Condensed Matter/Materials & Biological Physics Seminar with Geoffrey Diederich on Exciton dressing by extreme nonlinear magnons in a layered semiconductor

Collective excitations presenting nonlinear dynamics are fundamental phenomena with broad applications. A prime example is nonlinear optics, where diverse frequency mixing processes are central to communication, sensing, wavelength conversion, and attosecond physics. In this talk, I will present our recent results focused on the magnon behavior in the layered antiferromagnetic semiconductor CrSBr. I will demonstrate nonlinear opto-magnonic coupling to low order harmonics of the fundamental magnon. I will further show how we can create tunable optical sidebands from sum- and difference-frequency generation between two optically bright magnon modes under symmetry breaking magnetic fields. Moreover, the observed difference-frequency generation mode can be continuously tuned into resonance with one of the fundamental magnons, resulting in parametric amplification of magnons. Finally, I will show how we can access extreme high harmonic generation of the magnons by presenting exciton states dressed by up to 20 harmonics of magnons. These findings realize the modulation of the optical frequency exciton with the extreme nonlinearity of magnons at microwave frequencies, which could find applications in magnonics and hybrid quantum systems, and provide new avenues for implementing opto-magnonic devices.