Epitaxial Ferromagnetic Nanoislands of Cubic GdN in Hexagonal GaN

TL;DR

This study reports the epitaxial growth of GdN nanoislands within a GaN matrix, revealing their structural orientation, formation dynamics, and magnetic properties, including two distinct ferromagnetic phases.

Contribution

It introduces a method to create epitaxial GdN nanoislands in GaN and characterizes their structural and magnetic properties, including room temperature ferromagnetism.

Findings

GdN islands are epitaxially oriented to GaN matrix.

Island formation occurs after 1.2 monolayers of GdN coverage.

Two ferromagnetic phases are observed, one at 70K and one at room temperature.

Abstract

Periodic structures of GdN particles encapsulated in a single crystalline GaN matrix were prepared by plasma assisted molecular beam epitaxy. High resolution X-ray diffractometery shows that GdN islands, with rock salt structure are epitaxially oriented to the wurtzite GaN matrix. Scanning transmission electron microscopy combined with in-situ reflection high energy electron diffraction allows for the study of island formation dynamics, which occurs after 1.2 monolayers of GdN coverage. Magnetometry reveals two ferromagnetic phases, one due to GdN particles with Curie temperature of 70K and a second, anomalous room temperature phase.