Magnetic Compton profiles of Ni beyond the one-particle picture: numerically exact and perturbative solvers of dynamical mean-field theory

TL;DR

This paper investigates the magnetic Compton profiles of nickel using advanced density functional theory combined with dynamical mean-field theory, comparing different solvers and aligning theoretical results with experimental data.

Contribution

It introduces a comprehensive comparison of perturbative and numerically exact DMFT solvers for calculating magnetic properties of Ni, highlighting the impact of Coulomb interactions.

Findings

Total magnetic moment decreases with Coulomb repulsion U.

Experimental magnetic moments are matched at intermediate U values.

Fermi surface features are altered by electronic correlations.

Abstract

We calculated the magnetic Compton profiles (MCPs) of Ni using density functional theory supplemented by electronic correlations treated within dynamical mean-field theory (DMFT). We present comparisons between the theoretical and experimental MCPs. The theoretical MCPs were calculated using the KKR method with the perturbative spin-polarized T-matrix fluctuation exchange approximation DMFT solver, as well as with the full potential linear augmented planewave method with the numerically exact continuous-time quantum Monte Carlo DMFT solver. We show that the total magnetic moment decreases with the intra-atomic Coulomb repulsion $U$, which is also reflected in the corresponding MCPs. The total magnetic moment obtained in experimental measurements can be reproduced by intermediate values of $U$. The spectral function reveals that the minority X$_2$ Fermi surface pocket shrinks and gets shallower with respect to the density functional theory calculations.