Ferromagnetism and temperature-dependent Electronic Structure of hcp Gadolinium

TL;DR

This paper combines many-body models with ab initio calculations to analyze the temperature-dependent electronic structure and ferromagnetism of Gadolinium, achieving results close to experimental values.

Contribution

It introduces a method that integrates a multiband Kondo-lattice model with band structure calculations, accurately capturing temperature effects in Gd without double counting interactions.

Findings

Self-consistently derived Curie temperature of 294.1 K

T=0 magnetic moment of 7.71 μ_B

Explanation of photoemission data through temperature-dependent bands

Abstract

We use a combination of a many-body model analysis with an ab initio band structure calculation to derive the temperature dependent electronic quasiparticle structure of the rare-earth metal Gadolinium. As a local-moment system Gd is properly represented by the ferromagnetic (multiband) Kondo-lattice model (s-f (d-f) model). The single-particle part of the model-Hamiltonian is taken from an augmented spherical wave (ASW) band calculation. The proposed method avoids the double counting of relevant interactions by exploiting an exact limiting case of the model and takes into account the correct symmetry of atomic orbitals. The a priori only weakly correlated 5d conduction bands get via interband exchange coupling to the localized 4f levels a distinct temperature dependence which explains by a Rudermann-Kittel-Kasuya-Yosida (RKKY) -type mechanism the ferromagnetism of Gd. We get a self-consistently derived Curie temperature of 294.1 K and a T=0-moment of 7.71 $\mu_{\rm B}$, surprisingly close to the experimental values. The striking induced temperature-dependence of the 5d conduction bands explains respective photoemission data. The only parameter of the theory (interband exchange coupling J) is uniquely fixed by the band calculation.