Effects of proton irradiation on the magnetic properties of GaGdN and GaCrN

Abstract

GaGdN and GaCrN films grown by gas source molecular beam epitaxy were irradiated with high energy (10 and 40 MeV) protons at a fluence of 5 × 109 cm−2 to examine the effect on magnetization. This dose is equivalent to the exposure expected in 10 years in low-earth orbit space missions. Both photoluminescence intensity and magnetization of the films showed significant decreases with irradiation. The largest response was observed with GaGdN, which experienced a 50–60% loss in band edge luminescence and 11–83% loss in magnetic saturation. After annealing the irradiated samples at 500 ° C under a nitrogen plasma ambient, both types of films experienced a complete recovery in magnetic properties. The fact that the introduction of point defects did not increase the magnetization is evidence against unpaired bonds from defects in the film being responsible for the magnetic properties in the films.