Solid phase epitaxy of ferromagnetic MnAs dots on GaMnAs layers

TL;DR

This study demonstrates the formation of MnAs quantum dots on GaMnAs layers through low-temperature annealing, revealing a new method to create ferromagnetic nanostructures with potential applications in spintronics.

Contribution

It introduces a novel approach to form ferromagnetic MnAs quantum dots on GaMnAs layers via low-temperature annealing and Mn out-diffusion.

Findings

MnAs quantum dots form on (GaMn)As surfaces after annealing.

Quantum dots appear in layers thicker than 500 Å with 5% Mn.

Thinner layers exhibit smooth, well-ordered Mn-rich surface structures.

Abstract

Formation of MnAs quantum dots in a regular ring-like distribution has been found on MBE-grown (GaMn)As surfaces after low-temperature annealing under As capping. The Mn was supplied by out-diffusing Mn interstitials from (GaMn)As. With 5 at% substitutional Mn the quantum dots appeared for (GaMn)As layers thicker than 500 A. For thinner layers the Mn-rich surfaces, presumably monolayer thick MnAs, are smooth and well-ordered (1x2), and are well suited for continued epitaxial growth.