Layer-dependent band dispersion and correlations using tunable soft X-ray ARPES

Abstract

Soft X-ray Angle-Resolved Photoemission Spectroscopy is applied to study\nin-plane band dispersions of Nickel as a function of probing depth. Photon\nenergies between 190 and 780 eV were used to effectively probe up to 3-7\nlayers. The results show layer dependent band dispersion of the Delta_2\nminority-spin band which crosses the Fermi level in 3 or more layers, in\ncontrast to known top 1-2 layers dispersion obtained using ultra-violet rays.\nThe layer dependence corresponds to an increased value of exchange splitting\nand suggests reduced correlation effects in the bulk compared to the surface.\n