Exchange splitting ofsp-like surface states on Ni(001)

Abstract

Spin-resolved inverse photoemission is employed to investigate crystal-induced and image-potential surface states on Ni(001). The observed value of the spin splitting for the crystal-induced state at X¯ is 180±60 meV and there is experimental evidence of a nonvanishing exchange splitting of the image-potential state at Γ¯. These data are consistently described within the framework of a multiple-reflection model for surface states if the upper band-gap boundaries are assumed to be exchange split by 200 meV at Γ¯ and 230 meV at X¯. For Γ¯, this splitting was confirmed experimentally by spin-resolved target-current spectroscopy.