Electronic structure and x-ray magnetic circular dichroism of YBa2Cu3O7/LaMnO3 superlattices from first-principles calculations

TL;DR

This study uses first-principles calculations to elucidate the origin of x-ray magnetic circular dichroism in YBa2Cu3O7/LaMnO3 superlattices, revealing the role of hybridization and minor hole populations in the observed spectra.

Contribution

It demonstrates that small hybridization-induced holes in Cu 3z2-1 states cause XMCD, providing a detailed microscopic understanding of the phenomenon.

Findings

XMCD spectra are proportional to the difference in spin densities of Cu 3z2-1 states.

Minority and majority spin density differences drive the XMCD signal.

Hybridization across the interface creates holes sufficient to produce observable XMCD.

Abstract

The origin of x-ray magnetic circular dichroism (XMCD) at the Cu L2,3 edge in YBa2Cu3O7/La(1-x)Ca(x)MnO3 superlattices is revealed by performing first-principle electronic structure calculation using fully-relativistic spin-polarized linear muffin-tin orbital and projected augmented plane wave methods. We show that the XMCD spectra at the Cu L2,3 edges are proportional to the difference of the densities of majority- and minority-spin Cu 3z2-1 states. Although the Cu 3z2-1 states lie well below the Fermi level, a small number of majority-spin 3z2-1 holes is created by the Cu 3z2-1 - O p_z - Mn 3z2-1 hybridization across the interface. Even this tiny number of holes is sufficient to produce appreciable Cu L2,3 XMCD. The robustness of this conclusion is verified by studying the influence of doping, atomic relaxation, correlation effects, and antiferromagnetic order in a CuO2 plane on the XMCD spectra.