  We have investigated the electronic states and spin polarization of
half-metallic ferromagnet CrO$_2$ (100) epitaxial films by bulk-sensitive
spin-resolved photoemission spectroscopy with a focus on non-quasiparticle
(NQP) states derived from electron-magnon interactions. We found that the
averaged values of the spin polarization are approximately 100% and 40% at 40 K
and 300 K, respectively. This is consistent with the previously reported result
[H. Fujiwara et al., Appl. Phys. Lett. 106, 202404 (2015).]. At 100 K, peculiar
spin depolarization was observed at the Fermi level ($E_{F}$), which is
supported by theoretical calculations predicting NQP states. This suggests the
possible appearance of NQP states in CrO$_2$. We also compare the temperature
dependence of our spin polarizations with that of the magnetization.
