Magnonics at the Nanoscale in Terahertz Cavities

Objective

Controlling magnetism with light at the nanoscale is essential for developing ultrafast information technologies such as terahertz-speed data processing, energy-efficient signal transmission, and hybrid quantum devices. Magnons, the quantized spin-wave excitations in magnetically ordered materials, naturally oscillate in the terahertz regime in antiferromagnets and transport spin without charge, making them promising carriers for low-loss, high-speed information transfer. Yet direct magnon–photon coupling is intrinsically weak; in the terahertz regime prior demonstrations have relied on bulk crystals or extreme free-space fields, which are incompatible with scalable device architectures. This challenge is magnified in two-dimensional (2D) van der Waals magnets, where the reduced interaction volume suppresses coupling further. MagNaTeC addresses this obstacle by developing subwavelength metamaterial cavities that amplify the magnetic field of light, enabling ultrastrong coupling of magnons and photons in monolayer FePS₃. Building on my expertise in terahertz cavity quantum electrodynamics, I will realize magnon-polaritons in the ultrastrong regime and extend this platform to nonlinear spectroscopy of cavity magnonics. The host laboratory of Prof. Andrea Cavalleri at the Max Planck Institute for the Structure and Dynamics of Matter provides the ideal environment with world-leading expertise in strong-field terahertz spectroscopy. This project will pioneer magnetic-field-enhancing cavity architectures, establish the first demonstration of ultrastrong magnon–photon coupling in a 2D antiferromagnet, and reveal nonlinear interactions. These results will advance fundamental cavity quantum electrodynamics with spin systems, lay the scientific foundation for energy-efficient magnonic circuits, and provide me with the interdisciplinary training and leadership skills to launch an independent career at the interface of condensed matter physics and quantum information science.