Fig. 2: Coherent spin precession in the FM, SkL, and Cyc phases.

a Δθ traces in the first 800 ps shown with fit curves (black solid lines) at 10 K. b Coherent oscillatory component of the data shown in a. c, d Magnetic-field dependence of the frequency and amplitude of the coherent oscillation. The blue-shaded areas are guides to the eye indicating where the magnetic phase transition occurs. e, f Temperature dependence of the frequency and lifetime of the coherent oscillation, with the magnetic field fixed at 30 mT (60 mT) for the Cyc (SkL) phase. Error bars are the standard deviation of the fitting parameters.