On the origin of surface states in a correlated local-moment film

TL;DR

This paper investigates the origin of surface states in a correlated ferromagnetic local-moment film using an extended s-f model, revealing how surface modifications influence electronic structure and correlation effects.

Contribution

The study extends the s-f model to include surface effects by modifying hopping integrals, demonstrating the emergence of surface states for both spin orientations.

Findings

Surface states exist for spin-up and spin-down electrons due to surface modifications.

Correlation effects are significant for spin-down electrons in the model.

Surface modifications influence the electronic spectral density near the surface.

Abstract

The electronic quasiparticle structure of a ferromagnetic local moment film is investigated within the framework of the s-f model. For the special case of a single electron in an otherwise empty energy band being exchange coupled to a fully ordered localised spin system the problem can be solved exactly and, for the spin-down electron, some marked correlation effects can be found. We extend our model to incorporate the influence of the surface on the electronic structure. Therefore we modify the hopping integrals in the vicinity of the surface. This leads to the existence of surface states, both for the spin-up and the spin-down spectral density of states. The interplay between the modification of the hopping integrals and the existence of surface states and correlation effects is discussed in detail.