Field driven recovery of the collective spin dynamics of the chiral soliton lattice

We investigate the magnetic field dependence of the spin excitation spectra of the chiral soliton lattice (CSL) in the helimagnet CrNb₃S₆, by means of microwave resonance spectroscopy. The CSL is a prototype of a noncollinear spin system that forms periodically over a macroscopic length scale. Following the field initialisation of the CSL, we found three collective resonance modes over an exceptionally wide frequency range. With further reducing the magnetic field towards 0 T, the spectral weight of these collective modes was disrupted by the emergence of additional resonances whose Kittel-like field dependence was linked to coexisting field polarised magnetic domains. The collective behaviour at a macroscopic level was only recovered upon reaching the helical magnetic state at 0 T. The magnetic history of this non collinear spin system can be utilized to control microwave absorption, with potential use in magnon driven devices.