Magnetically active vacancy related defects in irradiated GaN layers

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.Comment: 3 pages, 3 figure

Spin Polarization and Magnetic Properties of VGaON and VGaONInGa in GaN: GGA+U Approach

“…Comparing the obtained results with experiments, we note that, according to the results, the observed collective ferromagnetism in GaN systems [7][8][9][10][11] can originate from magnetic interaction between V Ga O N defects. And in Ga-rich InGaN alloys, we predict even stronger FM.…”

“…III-nitride materials such as GaN and InGaN have found their applications in advanced solid-state lighting technologies [1][2][3] and optoelectronic devices including diodes or solar cells [4][5][6]. Moreover, the ferromagnetism (FM) in GaN or InN without doping by transition metal atoms was recently observed [7][8][9][10][11]. This FM was ascribed to the formation of native defects, such as cation vacancies or their complexes.…”

“…For example in Ref. [9], analysis of the characteristics of hysteresis curves in irradiated GaN showed that the coercive field increases in line with the increase of concentration of gallium vacancy (V Ga ). The stable FM was discovered in n-type GaN, and it can be due to the presence of non-intentional donors, such as oxygen.…”

Vacancy complexes induce long-range ferromagnetism in GaN

“…5 Besides magnetically active complexes involving Ga vacancies in pristine GaN, 6 also GaN vacancies (V GaN ) in Mg and Er doped GaN and GaN vacancy complexes have been confirmed. 15,16 In this work, we will demonstrate long-range ferromagnetism induced by vacancy complexes in wurtzite GaN, incorporating both V Ga and V N , rather than the previously proposed V Ga induced ferromagnetism.…”

“…5,6 A special case is Gd-doped GaN, for which colossal magnetic moments have been reported. 3 Subsequent studies found the Gd atoms to behave paramagnetically and showed only weak indications of moment formation for the Ga atoms.…”