Enhancement of the magnetic properties in (Ga1−xMnx)N thin films due to Mn-delta doping

Abstract

The effects of Mn delta-doping on the magnetic properties of (Ga1−xMnx)N thin films grown on GaN buffer layers by molecular-beam epitaxy were studied. The magnetization curve as a function of the magnetic field as 5K indicated that ferromagnetisms existed in the Mn delta-doped (Ga1−xMnx)N and (Ga1−xMnx)N thin films and that the magnetization in the Mn delta-doped (Ga1−xMnx)N thin film was significantly enhanced. The magnetization curve as a function of the temperature showed that the Curie temperature of the Mn delta-doped (Ga1−xMnx)N thin film was estimated to be above room temperature. The increase of the magnetization in the Mn delta-doped (Ga1−xMnx)N thin film in comparison with that in the (Ga1−xMnx)N thin film was attributed to the enhancement of the carrier-mediated ferromagnetism due to increased hole concentrations. The theoretical results showed that Ga vacancies near the Mn delta-doping layer were likely to cause p-type conductance, indicating that the enhancement of the magnetic properties in (Ga1−xMnx)N thin films originated from Mn delta doping.

The electronic and magnetic properties of Mn-doped GaN

“…We also investigate the electronic structure of Mn-doped GaN. We find that Ga vacancies can be stabilized near the Mn-doped layer due to the charge transfer from the Mn layer to Ga vacancies, suggesting that Ga vacancies near the Mn layer are responsible for p-type conductivity recently observed in Mn-doped GaMnN films [4].Our calculations are performed within the local-spindensity-functional approximation (LSDA) using the gradient correction for the exchange-correlation energy [5]. Ultrasoft pseudopotentials [6] are used for the efficient treatment of localized orbitals.…”

“…We also investigate the electronic structure of Mn-doped GaN. We find that Ga vacancies can be stabilized near the Mn-doped layer due to the charge transfer from the Mn layer to Ga vacancies, suggesting that Ga vacancies near the Mn layer are responsible for p-type conductivity recently observed in Mn-doped GaMnN films [4].…”

Digital magnetic heterostructures based on GaN using GGA-1/2 approach

“…9 DMH has already been achieved experimentally for GaAs d-doped with Mn, leading to T c ¼ 250 K. 10 Another good example is GaMnN monolayers (MLs) embedded in GaN: this d-doping technique permits not only to synthesize GaMnN ML with a Mn composition much higher than the one achievable with bulk-GaMnN, but also to enhance the magnetization and the T c of the sample. [11][12][13] A DMH has also been proposed for Si, to overcome the difficulty of Mndoping.…”

Ferromagnetism of Mn-doped GaN polycrystalline powders

“…Some researchers even observed paramagnetic instead of ferromagnetic ordering in the Mn-doped GaN samples [14,15]. Furthermore, the concentrations of Mn-induced ferromagnetic ordering are scattered, distributing from 0.9 [8], 3-12 [9] to 0.7-2.8 at% [11]. In fact, at present most of research focus on Mndoped GaN thin films.…”

“…However, the experimental results reported by different groups are not well consistent. For instance, the T c of Mn-doped GaN is in a wide range, from 10-25 [3], 228-370 [4], 250 K [5,6], near RT or above RT [7][8][9][10], up to 940 K [11]. Additionally, some authors attributed ferromagnetic ordering of the Mn-doped GaN samples to Mn-rich clusters or Ga-Mn magnetic phases [12,13].…”