Spin Dynamics Mode Locking between Helimagnetism and Ferromagnetism

Non-collinear spin textures, such as spin spirals and skyrmions, exhibit rich emergent physics in their spin dynamics. Nevertheless, the potential to exploit their distinctive spin resonance characteristics for on-chip microwave magnonic applications remains elusive. Here, we investigate the microwave emission and mode coupling from the resonating spin spiral lattice in a Cu2OSeO3/Pt/NiFe heterostructure. Using time-resolved resonant elastic x-ray scattering, the exact vectorial spin precession modes from the two magnetic species are visualized in real-time. Our results show that the NiFe layer captures the excitation modes from the conical order in Cu2OSeO3 by exhibiting a ferromagnetic resonance behaviour. The NiFe spin precession is fully synchronized with the helimagnet, presenting unique dynamics with chiral symmetry. This demonstrates that helimagnons can wirelessly transmit spin information in gigahertz-level frequency, enabling new possibilities for on-chip microwave magnonics.