Effect of growth conditions on the magnetic characteristics of GaGdN

Abstract

GaGdN layers were grown by gas source molecular beam epitaxy with varying crystal quality and Gd concentrations as set by the Gd cell temperature. Magnetic measurements showed ferromagnetic behavior at room temperature, with the saturation magnetization dependent both on Gd concentration and crystalline quality. The Gd concentration was under the detection limit of secondary ion mass spectrometry, and estimated to be on the order of <1017at.∕cm3. As expected at this low dopant concentration, x-ray diffraction measurements showed the films to be single phase. Gd-doped samples codoped with Si to make them conducting with resistivity of 0.04Ωcm showed similar magnetic properties as Gd-doped films without addition of Si.

Electron stabilized ferromagnetism in GaGdN

“…Their samples are highly resistive which shows a strong influence of the Gd doping on the electrical conductivity even though Gd is isovalent to Ga in GaN and thus no change in the electric behavior compared to GaN is expected for substitutional incorporation on a Ga-site. Also other groups found ferromagnetic behavior at room temperature and high resistivity in GaGdN [2][3][4]. A theoretical work by Dalpian and Wei [5] supports that Gd in GaN might give rise to such huge moments due to hybridization effects of the s-like conduction band and the f-states of the Gd atom.…”

X-ray absorption in GaGdN: A study of local structure

“…6,7 Moreover, according to a recent theoretical work, Ga vacancies are the most effective source of localized holes necessary for a strong ferromagnetic p-d exchange coupling in GaGdN. 8 In addition, several reports have not detected the formation of any secondary phases in GaN, 9,10 whereas in Gd implanted GaN the presence of precipitates of Gd 3 Ga 2 , GdN, and Gd has been observed with high saturation magnetization. 11 Therefore, the role of Gd on the defect formation, local atomic site configuration, and/or phase separation in GaN is of key importance.…”

Studies on the InGaGdN/GaN magnetic semiconductor heterostructures grown by plasma-assisted molecular-beam epitaxy

“…Previously, our group reported on the room-temperature ferromagnetism of the rareearth element Gd-doped GaN: GaGdN [5,6]. Such interesting findings on the achievable ferromagnetism of rare earth-nitride systems have sparked interest in research activities either experimentally or theoretically to further elucidate the magnetism of this type of rare earth-doped binary compounds [7][8][9][10]. Most of the works reported in DMSs are mainly on binary alloys, only a few works have been reported on rare earth-doped ternary compounds especially in InGaN [11][12][13].…”