Strong Spin Dependence of Correlation Effects in Ni Due to Stoner Excitations

Abstract

Using high resolution angle resolved photoemission, we observe a strong spin dependent renormalization and lifetime broadening of the quasiparticle excitations in the electronic band structure of Ni 111 in an energy window of amp; 8764;0.3 eV below the Fermi level. We derive a quantitative result for the spin dependent lifetime broadening by comparing the scattering rates of majority and minority d states, and further show that spin dependent electron correlations are instead negligible for sp states. From our analysis we experimentally determine the effective on site Coulomb interaction U caused by Stoner like interband transitions between majority and minority d states. The present results demonstrate the remarkable impact of spin dependent electron correlation effects originating from single particle excitations in a prototypical 3d transition metal, paving the way for further refinement of current many body theoretical approache