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

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 (Γ̄) are determined. All investigated states are found to have a sizable exchange splitting >50 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 S1 has an occupied majority and an unoccupied minority band with a splitting Δ Eex =62±15 meV. The surface states below the Fermi energy show a larger exchange splitting for in-plane hybridization [Δ Eex (S3) =160 meV] than for out-of-plane hybridization [Δ Eex (S2) =55meV].