Observation of spin dynamics associated with exotic helical spin orders in EuIn₂As₂

Layered antiferromagnetic materials provide a fertile playground for probing exotic magnetic orders, as well as for developing new approaches to manipulate magnetization dynamics for novel spintronic devices. In order to harness the excitations associated with these unconventional magnetic phases, it is crucial to characterize the largely unexplored collective spin modes that emerge within them. In this talk, I focus on our recent all-optical studies of time-resolved spin dynamics in the helical antiferromagnet EuIn₂As₂, wherein we detect magnons associated with distinct and broken helical spin phases for the first time. We demonstrate the evolution of these coherent magnon modes with magnetic field and temperature, illustrating their emergence with different magnetic orders, and use this to describe the magnetic phase diagram and dynamical spin landscape in EuIn₂As₂.