Magnetically active vacancy related defects in irradiated GaN layers

TL;DR

This study investigates how irradiation-induced gallium vacancies in GaN layers lead to magnetic properties, revealing superparamagnetic behavior and the role of vacancy complexes in magnetism.

Contribution

It demonstrates controllable creation of Ga vacancies via irradiation and links vacancy complexes to magnetic moments in GaN, a novel insight.

Findings

Magnetic moments observed with concentrations of 4.3-8.3x10^17 cm^-3.

Superparamagnetic blocking at room temperature.

Hysteresis with coercive field of 270 Oe at 5 K.

Abstract

We present the studies of magnetic properties of 2 MeV 4He+-irradiated GaN grown by metal-organic chemical-vapor deposition. Particle irradiation allowed controllable introduction of Ga-vacancy in the samples. The magnetic moments with concentrations changing between 4.3...8.3x10^17 cm^-3 showing superparamagnetic blocking at room temperature are observed. The appearance of clear hysteresis curve at T = 5 K with coercive field of about H_C = 270 Oe suggests that the formation of more complex Ga vacancy related defects is promoted with increasing Ga vacancy content. The small concentration of the observed magnetically-active defects with respect to the total Ga- vacancy concentration suggests that the presence of the oxygen/hydrogen-related vacancy complexes is the source of the observed magnetic moments.