Exchange splitting of the threeΓ¯surface states of Ni(111) from three-dimensional spin- and angle-resolved photoemission spectroscopy

Abstract

The valence-band electronic structure of a clean Ni(111) surface is investigated by spin-resolved photoemission. At room temperature the orientation of the photoelectron spins on the Bloch sphere and the exchange splitting of surface and bulk states along the surface normal $(\overline{\ensuremath{\Gamma}})$ are determined. All investigated states are found to have a sizable exchange splitting $g50\text{ }\text{meV}$. Since the splitting is smaller than the intrinsic line width in the spin-integrated spectrum this is only seen with a spin-resolved technique. At room-temperature photoemission reaching above the Fermi level directly shows that the Shockley type surface state ${S}_{1}$ has an occupied majority and an unoccupied minority band with a splitting $\ensuremath{\Delta}{E}_{ex}=62\ifmmode\pm\else\textpm\fi{}15\text{ }\text{meV}$. The surface states below the Fermi energy show a larger exchange splitting for in-plane hybridization $[\ensuremath{\Delta}{E}_{ex}({S}_{3})=160\text{ }\text{meV}]$ than for out-of-plane hybridization $[\ensuremath{\Delta}{E}_{ex}({S}_{2})=55\text{ }\text{meV}]$.