Energy band and spin-dependent many-body interactions in ferromagnetic Ni(110): A high-resolution angle-resolved photoemission study

Abstract

High-resolution angle-resolved photoelectron spectroscopy of ferromagnetic Ni(110) has been conducted to elucidate energy band and spin-dependent many-body interactions. A kink structure has been clearly observed in the energy band dispersions of the minority spin ${\ensuremath{\Sigma}}_{2\ensuremath{\downarrow}}$ and ${\ensuremath{\Sigma}}_{1\ensuremath{\downarrow}}$, while it is absent in the majority spin ${\ensuremath{\Sigma}}_{1\ensuremath{\uparrow}}$ band. Analyses of the self-energy indicate that the kink originates from the electron-phonon interaction. Based on a detailed study of the effective mass enhancement, we find that the electron-phonon interaction and electron correlation contribute to the spectral features near the Fermi level in different ways, depending on the identity of the energy band and the spin direction. These results provide insight into the interplay of these many-body interactions on quasiparticles near the Fermi level.