First-principles study of nucleation, growth, and interface structure of Fe/GaAs

TL;DR

This study uses density-functional theory to investigate the initial stages of Fe film growth on GaAs(001), revealing key interactions, interface structures, and magnetic behaviors that influence film formation.

Contribution

It provides a detailed first-principles analysis of Fe/GaAs interface chemistry, magnetism, and growth mechanisms, highlighting the role of adlayers and atomic diffusion.

Findings

Submonolayer Fe-GaAs interactions involve substitutional adsorption.

Atomically abrupt interfaces are energetically favored for thicker films.

Ga and As adlayers act as surfactants, reducing formation energies.

Abstract

We use density-functional theory to describe the initial stages of Fe film growth on GaAs(001), focusing on the interplay between chemistry and magnetism at the interface. Four features appear to be generic: (1) At submonolayer coverages, a strong chemical interaction between Fe and substrate atoms leads to substitutional adsorption and intermixing. (2) For films of several monolayers and more, atomically abrupt interfaces are energetically favored. (3) For Fe films over a range of thicknesses, both Ga- and As-adlayers dramatically reduce the formation energies of the films, suggesting a surfactant-like action. (4) During the first few monolayers of growth, Ga or As atoms are likely to be liberated from the interface and diffuse to the Fe film surface. Magnetism plays an important auxiliary role for these processes, even in the dilute limit of atomic adsorption. Most of the films exhibit ferromagnetic order even at half-monolayer coverage, while certain adlayer-capped films show a slight preference for antiferromagnetic order.