320 research outputs found
Transition from Ferromagnetism to Antiferromagnetism in GaMnN
Using density functional theory, we study the magnetic stability of the
GaMnN alloy system. We show that unlike GaMnAs, which
shows only ferromagnetic (FM) phase, GaMnN 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
Surface magnetization in non-doped ZnO nanostructures
We have investigated the magnetic properties of non-doped ZnO nanostructures
by using {\it ab initio} total energy calculations. Contrary to many proposals
that ferromagnetism in non-doped semiconductors should be induced by intrinsic
point defects, we show that ferromagnetism in nanostructured materials should
be mediated by extended defects such as surfaces and grain boundaries. This
kind of defects create delocalized, spin polarized states that should be able
to warrant long-range magnetic interactions.Comment: 8 pages, 3 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
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