Apr 9, 2025
9:30am - 10:00am
Summit, Level 3, Room 343
Honglie Ning1,Nuh Gedik1
Massachusetts Institute of Technology1
Coherent manipulation of magnetism via lattice provides unprecedented opportunities for controlling spintronic functionalities on the ultrafast timescale. By coherently driving magnons and phonons in the THz spectral range, a vast array of phenomena can emerge from their intricate coupling. Here, I will present two demonstrations by leveraging the strong coupling between magnons and Raman-active phonons in van der Waals antiferromagnets. First, I will discuss how this interaction facilitates both linear and quadratic excitation of magnon-polarons — magnon-phonon hybrid quasiparticles — using intense THz pulses. This approach provides an innovative method to control quasiparticle dynamical symmetry by tuning the THz field strength and polarization. The polarimetry of the resulting coherent oscillation amplitude reveals a breaking of the crystallographic C
2 symmetry, driven by strong interference between the two excitation channels. Second, I will demonstrate how nondegenerate chiral phonons can be induced by coupling to chiral magnons. Such nondegeneracy enables their coherent excitation with linearly polarized terahertz pulses. By tuning the terahertz drive polarization and measuring phase-resolved polarimetry of the resulting coherent oscillations, we can determine the ellipticity and map the trajectory of these hybrid quasiparticles. Our findings outline a novel roadmap towards phonon-controlled spintronic functionalities and unlock a wide range of possibilities to manipulate material properties, ranging from generation of metastable magnetic states via displacive phonon excitation to the modulation of exchange interactions by phonon-Floquet engineering.