Transition from Ferromagnetism to Antiferromagnetism in Ga1−x_{1-x}Mnx_xN

Using density functional theory, we study the magnetic stability of the Ga$_{1-x}$Mn$_x$N alloy system. We show that unlike Ga$_{1-x}$Mn$_x$As, which shows only ferromagnetic (FM) phase, Ga$_{1-x}$Mn$_x$N can be stable in either FM or antiferromagnetic phases depending on the alloy concentration. The magnetic order can also be altered by applying pressure or with charge compensation. A unified model is used to explain these behaviors.Comment: 4 pages, 4 figure

Barrierless procedure for substitutionally doping graphene sheets with boron atoms: ab initio calculations

Using ab initio methods, we propose a simple and effective way to substitutionally dope graphene sheets with Boron. The method consists of selectively exposing each side of the graphene sheet to different elements. We first expose one side of the membrane to Boron, while the other side is exposed to Nitrogen. Proceeding this way, the B atoms will be spontaneously incorporated into the graphene membrane, without any activation barrier. In a second step, the system should be exposed to a H-rich environment, that will remove the CN radical from the layer and form HCN, leading to a perfect substitutional doping.Comment: Accepted Physical Review