  In the cubic chiral magnet Cu2OSeO3 a low-temperature skyrmion state (LTS)
and a concomitant tilted conical state are observed for magnetic fields
parallel to <100>. In this work, we report on the dynamic resonances of these
novel magnetic states. After promoting the nucleation of the LTS by means of
field cycling, we apply broadband microwave spectroscopy in two experimental
geometries that provide either predominantly in-plane or out-of-plane
excitation. By comparing the results to linear spin-wave theory, we clearly
identify resonant modes associated with the tilted conical state, the
gyrational and breathing modes associated with the LTS, as well as the
hybridization of the breathing mode with a dark octupole gyration mode mediated
by the magnetocrystalline anisotropies. Most intriguingly, our findings suggest
that under decreasing fields the hexagonal skyrmion lattice becomes unstable
with respect to an oblique deformation, reflected in the formation of elongated
skyrmions.
