Properties Of Diluted Magnetic Semiconductor: First-principles Calculations

Modern electronic devices utilize the charge degree of freedom of electrons to process information and the spin degree of freedom to store information. If both the charge and spin of electrons can be combined, we many be able to accomplish mass storage and information processing at the same time. In this way the performance of electronic devices will be enhanced.First-principles methods based upon density functional theory are performed for diluted magnetic semiconductor. Most of the calculations are performed by using Discrete Variational cluster approach within local density approximation.Thus density functional theory (DFT) is introduced. The Discrete Variational Method (DVM) for clusters (DFT in real space) is described in detail. The basis functions, numerical grids utilized and potential are discussed.The local electronic structure and magnetic properties of diluted magnetic semiconductor (Ga,Cr)N have been studied by using DVM based on density functional theory. The magnetic moments per Cr atom vary significantly with Cr concentration, and the trend of variation is in agreement with that of the experiment. The coupling between Cr atoms in the system with two Cr atoms considered is found to be ferromagnetic, and the magnetic moment per Cr atom is similar to the case in which only one Cr atom is considered in the same doping concentration. For all doping concentrations, the coupling between Cr and the nearest neighbor N is found to be antiferromagnetic, and the Cr 3d states hybridize strongly with N 2p states, which are in agreement with the band calculations. The local electronic structure and magnetic properties of diluted magnetic semiconductor (Ga,Mn)As has also been studied by using Discrete Variational approach based.