Stable and Metastable Structures of Cobalt on Cu(001): An ab initio Study

TL;DR

This study uses density-functional theory to explore the structural, magnetic, and electronic properties of cobalt on copper (001) surfaces, revealing stable configurations, phase separation tendencies, and magnetic interactions.

Contribution

It provides new insights into the stable and metastable structures of Co on Cu(001), including the lowest-energy bilayer and alloy formations, and their magnetic properties.

Findings

Bilayer Co film covered by 1ML Cu is lowest-energy structure.

Co adlayers induce weak spin-density waves in Cu substrate.

Possible formation of bilayer c(2x2)-alloy due to kinetic or strain effects.

Abstract

We report results of density-functional theory calculations on the structural, magnetic, and electronic properties of (1x1)-structures of Co on Cu(001) for coverages up to two monolayers. In particular we discuss the tendency towards phase separation in Co islands and the possibility of segregation of Cu on top of the Co-film. A sandwich structure consisting of a bilayer Co-film covered by 1ML of Cu is found to be the lowest-energy configuration. We also discuss a bilayer c(2x2)-alloy which may form due to kinetic reasons, or be stabilized at strained surface regions. Furthermore, we study the influence of magnetism on the various structures and, e.g., find that Co adlayers induce a weak spin-density wave in the copper substrate.