  Magnetic diffraction in combination with x-ray detected ferromagnetic
resonance (DFMR) is a powerful technique for performing time-resolved
measurements on individual spin textures. Here, we study the ferromagnetic
resonance (FMR) modes of both the conical and field-polarized phases in the
chiral magnet Cu$_2$OSeO$_3$. Following the identification of the FMR modes at
different temperatures using broadband vector network analyzer FMR, we use DFMR
on the crystalline (001) Bragg peak to reveal the time-dependent spin
configurations of the selected FMR modes. By being able to measure both the
amplitude and phase response of the spin system across the resonance, a
continuous phase advance (of 180$^\circ$) in the conical mode, and a phase lag
(of 180$^\circ$) in the field-polarized mode is found. By performing dynamic
measurements in the conical phase as a function of the linear polarization
angle of the x-rays, i.e., successively probing the dynamics of the moments, we
find an inversion of the dynamics along the conical axis upon inverting the
applied field direction. By allowing for time-resolved measurements of the
phase and amplitude of individual magnetic phases, DFMR opens up new
opportunities for obtaining a deeper understanding of the complex dynamics of
chiral magnets.
