LDA++ approach to electronic structure of magnets: correlation effects in iron

TL;DR

This paper introduces the LDA++ approach for analyzing correlation effects in magnetic materials, specifically ferromagnetic iron, incorporating frequency-dependent self-energy and generalized fluctuation exchange approximation.

Contribution

It develops a novel LDA++ method that accounts for frequency dependence in self-energy and extends the fluctuation exchange approximation to spin-polarized multi-band systems.

Findings

Fermi liquid behavior near the Fermi level in iron

Strong damping of quasiparticle states beyond 1 eV

Satisfactory explanation of spin-polarized thermoe emission data

Abstract

A novel approach to investigation of correlation effects in the electronic structure of magnetic crystals which takes into account a frequency dependence of the self energy (so called ``LDA++ approach'') is developed. The fluctuation exchange approximation is generalized to the spin-polarized multi-band case and its local version is proposed. As an example, we calculate the electronic quasiparticle spectrum of ferromagnetic iron. It is shown that the Fermi liquid description of the bands near the Fermi level is reasonable, while the quasiparticle states beyond approximately 1 eV range are strongly damped, in agreement with photoemission data. The result of the spin-polarized thermoemission experiment is explained satisfactory. The problem of satellite structure is discussed.