Surface-bulk differences in the electronic structure of CaFe₂As₂

Abstract

We studied the electronic structure of CaFe₂As₂ using photoemission spectroscopy. The features in the x‐ray photoemission spectra could be described using band structure results. The electronic states close to the Fermi level are found to be dominated by the Fe 3d contributions. The valence band spectra exhibit significant dependence on the photon energy used for the experiments. A comparison of the spectra at different photon energies suggests that the temperature dependence of the bulk and surface electronic states are significantly different–the bulk Fe 3d states seem to be strongly temperature dependent while the surface states appear to be almost insensitive. These results have significant implication in the understanding of superconductivity in this class of materials.