Variation of exchange energy in δ-(Ga,Mn)As films under tensile strain: PBE and LDA+U calculations

Abstract

PBE and LDA+U calculations were both used to clarify the variation of exchange energy in three kinds of δ-(Ga,Mn)As films under tensile strain. All configurations were strong FM types regardless of which of the two methods was used under strain. Tensile strain could affect the exchange energy and the thickness of three kinds of films. In some configurations, the exchange energy could be enhanced by shape deformation. The thickness of δ-(Ga,Mn)As from LDA+U calculations was greater than from PBE with the same lattice constant in each structure. PBE showed strong double exchange, while LDA+U resulted in a p–d exchange between Mn atoms in the DOS structure. All such films could be grown layer-by-layer based on the formation energy thereof.