摘要
We report on a detailed quasiparticle interference (QPI) scattering study of the Ni(111) surface by low-temperature scanning tunneling spectroscopy (LT-STS). While conventional constant-separation STS shows two broad features, which are interpreted as the Λ3 bulk band and sp-like Shockley-type surface state (sp-SS), energy-dependent Fourier-transformed QPI maps reveal the band dispersion of the underlying surface electronic features. We find two electronlike branches in the sp-SS dispersion, which are interpreted as the exchange-split minority and majority spin part. The exchange splitting is determined to ΔEex=100±8 meV. In addition, a holelike d-derived surface resonance is found. Band onsets and effective electron masses are determined by fitting the band dispersion with a parabola at small k values. Hybridization effects with bulk electronic states are observed towards larger k values. Prominent quantum confinement phenomena of the sp-SS are observed in STS data obtained within vacancy islands. The results can be interpreted within a one-dimensional quantum-well model. © 2014 American Physical Society.