Nitrogen vacancy effects on the ferromagnetism of Mn doped GaN films

Abstract

The amorphous gallium nitride thin films doped with Mn were deposited by Laser assisted Molecular Beam Epitaxy (LMBE). After annealing at different NH 3 flow rates, the high-quality GaMnN crystalline films with different concentration of nitrogen vacancies (V N ) were obtained, which were confirmed by the X-ray diffraction spectroscopy and Raman measurements. The magnetic behaviors of these films were also obtained to investigate the effects of nitrogen vacancies. It indicates that V N play a significant role in the origin of ferromagnetism. The stronger room-temperature ferromagnetism is given with the higher V N concentration when it is not beyond a critical concentration. Moreover, from our M(T ) curves and Raman analysis, the films present high resistivity. The magnetism of films with high resistivity varies with concentration of nitrogen vacancies, which can be explained by the bound magnetic polarons (BMP) theory.

Enhanced Ferromagnetism in Nanoscale GaN:Mn Wires Grown on GaN Ridges

“…These lattice disorders and built-in defects disrupt the long-range ionic ordering in GaN, thus weakening the electric field associated with the LO mode, and thus lowering its frequency. All of the results showed a correlation between the built-in defects and the ferromagnetic enhancement in the wire part, and thus supported the viewpoint that aside from the Mn doping rate, the built-in defects might play an important role in the magnetism of GaN:Mn [ 39 , 40 , 41 , 42 ].…”

A hybrid density functional view of native vacancies in gallium nitride

“…Of particular interest are the intrinsic defects of GaN, such as Ga and N vacancies, which may form during growth and might act as doping compensators or interact more or less favorably with dopants, e.g. Mn [7] and Gd [8] impurities, which give rise to magnetic defects in GaN.…”