Dependence of the magnetic properties of MnGaN epitaxial layers on external electrical field

Investigation of the magnetic properties of MnGaN epitaxial layers as a function of external electrical field was performed on the basis of field effect structure. The structure included substrate of n-type GaN, epitaxial layer of n-type Mn(x)Ga(1-x)N, dielectric layer and metal layer acting as field effect device gate. Each Mn atom in Mn(x)Ga(1-x)N contributes 4 net spins due to the electrons occupying energy levels (4)F, (4)D, (4)P and (4)G belonging to 3d orbital, and these levels are in the energy band gap and in the top of the valence band of Mn(x)Ga(1-x)N. The position of the Fermi level is determined to be in the energy band gap of the layer of GaN and to be above the level 4F in the layer of Mn(x)Ga(1-x)N. In this way application of external negative voltage on the gate causes change in the number of electrons contributing net spins and the saturation magnetization M sat of Mn(x)Ga(1-x)N changes as well. It was found that M sat changes in the range 1.15 x 10(-3)-0.7 x 10-3 A mu m(-1) if the external voltage changes in the interval 0--5V. The application of this structure for the design of spintronic devices is discussed in this paper.