Surface magnetism of Mg doped AlN: a first principle study

Abstract

Using first-principles calculations, we have systematically investigated the magnetic properties of Mg-doped AlN (1 0 1 0) and (0 0 0 1) surfaces. Both the polar and non-polar surfaces are found to be magnetic and the magnetic moments are mainly due to spin polarized 2p orbitals of surface N atoms surrounding Mg. The splitting of energy levels in both cases favours charge hopping between the minority spin states of N 2p orbitals, which leads to a stable ferromagnetic ground state. However, the range of magnetic coupling and the stability of the ferromagnetic state differ between the polar and non-polar surfaces and are dependent on the nature of localization of the defect states. The ferromagnetic state in a Mg-doped reconstructed (0 0 0 1) surface is more stable than in a Mg-doped AlN (1 0 1 0) surface.

Density Functional Theory Study of Defect Induced Ferromagnetism and Half-Metallicity in CaI2 Based Monolayer for Spintronics Applications

“…Furthermore, due to strong d–d interactions, metal dopants in main group based materials tend to form clusters resulting in nonhomogenous magnetization . Consequently, researchers have favored main group based systems − over TM based systems due to their longer spin relaxation time, which is an important criterion for spintronics application. − …”

Effects of carbon doping on the electronic properties of boron nitride nanotubes: Tight binding calculation

“…While CNTs have been found to be either metallic or semiconducting [2], all the BNNTs are semiconductors with direct band gaps for zigzag tubes and indirect band gaps for armchair and chiral tubes [3]. The different properties of pure and doped sheet, nanoribbon and nanotube with other material such as GaN, AlN and SiC has been investigated [4][5][6][7][8][9][10][11]. The structure, electronic and conductivity properties of carbon doped BNNTs have been investigated by different methods [12][13][14][15][16][17].…”

Ferromagnetism of wide-bandgap semiconductor surfaces: Mg-doped AlN

“…In an earlier work, 25) we studied the magnetic properties of two surfaces of Mg-doped AlN; the polar ð000 1Þ surface and the non-polar ð10 10Þ surface. Both surfaces were found to be magnetic, and the magnetic moments are mainly due to spin-polarized 2p orbitals of surface N atoms surrounding Mg.…”

“…The electron wave function is expanded using plane waves with a cutoff energy of 500 eV. Similar to that in the previous study, 25) a slab model, with a supercell, which consists of 2 × 1 units of AlN in the plane of the surface and a thickness of 10 atomic layers, and a vacuum region of 12 Å in the normal direction of the surface is used for the calculation of a single defect in the ð11 20Þ surface, while a 3 × 2 supercell is used for the ð10 11Þ surface. The dangling bonds in the bottom layer are saturated with pseudohydrogen atoms.…”

“…There exist non equal numbers of cations and anions in the surface layer of a polar or semi-polar surface of AlN, and such surfaces are unstable and tend to reconstruct unless they are passivated. In the earlier study, 25) the reconstructed ð000…”