Thickness dependence of photoemission spectra in zinc-blende CrAs

The electronic structure of CrAs thin films with nominal thicknesses of 2 nm and 30 nm were studied by angle-resolved photoemission spectroscopy using synchrotron radiation. The CrAs film of 2 nm is expected to form a zinc-blende phase which is predicted to have a half-metallic band structure by theoretical calculation. On the other hand, it is considered that the CrAs film of 30 nm is a polycrystalline compound judging from reflection high-energy electron diffraction patterns. Different valence-band photoemission spectra were obtained for the two films. The photoemission spectra of the CrAs film of 30 nm showed no band dispersion, whereas a band dispersion was observed in that of the CrAs film with the nominal thickness of 2 nm.