Electron correlation effects and magnetic ordering at the Gd(0001) surface

TL;DR

This study uses advanced electronic structure calculations to show how electron correlation influences magnetic ordering and Curie temperature enhancement at the Gd(0001) surface, aligning well with experimental data.

Contribution

It demonstrates the importance of including electron correlation effects via LDA+U for accurately predicting magnetic properties of Gd surfaces.

Findings

LDA+U yields the correct ferromagnetic ground state.

Surface strain significantly enhances exchange coupling.

Curie temperature at the surface is increased by 30%.

Abstract

Effects of electron correlation on the electronic structure and magnetic properties of the Gd(0001) surface are investigated using of the full-potential linearized augmented plane wave implementation of correlated band theory ("LDA+U"). The use of LDA+U instead of LDA (local density approximation) total energy calculations produces the correct ferromagnetic ground state for both bulk Gd and the Gd surface. Surface strain relaxation leads to an 90 % enhancement of the interlayer surface-to-bulk effective exchange coupling. Application of a Landau-Ginzburg type theory yields a 30 % enhancement of the Curie temperature at the surface, in very good agreement with the experiment.