Electronic structure of La (0001) thin films on W (110) studied by photoemission spectroscopy and first principle calculations

Surface states that have a dz2 symmetry around the center of the surface Brillouin zone (BZ) have been regarded common in closely-packed surfaces of rare-earth metals. In this work, we report the electronic structure of dhcp La (0001) thin films by ultrahigh energy resolution angle-resolved photoemission spectroscopy (ARPES) and first principle calculations. Our first principle analysis is based on the many-body approach, therefore, density function theory (DFT) combined with dynamic mean-field theory (DMFT). The experimentally observed Fermi surface topology and band structure close to the Fermi energy qualitatively agree with first principle calculations when using a renormalization factor of between 2 and 3 for the DFT bands. Photon energy dependent ARPES measurements revealed clear kZ dependence for the hole-like band around the BZ center, previously regarded as a surface state. The obtained ARPES results and theoretical calculations suggest that the major bands of dhcp La (0001) near the Fermi level originate from the bulk La 5d orbits as opposed to originating from the surface states.