Layer dependent band dispersion and correlations using tunable Soft X-ray ARPES

TL;DR

This study uses tunable soft X-ray ARPES to investigate how the electronic band structure of Nickel varies with depth, revealing layer-dependent dispersion and correlation effects up to several atomic layers.

Contribution

It demonstrates the capability of soft X-ray ARPES to resolve layer-dependent electronic structures in Nickel, highlighting differences between surface and bulk properties.

Findings

Layer-dependent band dispersion observed in Nickel.

Fermi level crossing in 3 or more layers.

Reduced correlation effects in the bulk compared to surface.

Abstract

Soft X-ray Angle-Resolved Photoemission Spectroscopy is applied to study in-plane band dispersions of Nickel as a function of probing depth. Photon energies between 190 and 780 eV were used to effectively probe up to 3-7 layers. The results show layer dependent band dispersion of the Delta_2 minority-spin band which crosses the Fermi level in 3 or more layers, in contrast to known top 1-2 layers dispersion obtained using ultra-violet rays. The layer dependence corresponds to an increased value of exchange splitting and suggests reduced correlation effects in the bulk compared to the surface.