Observation of Intrinsic Half-metallic Behavior of CrO$_2$ (100) Epitaxial Films by Bulk-sensitive Spin-resolved PES

摘要

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