Shape deformation induced enhancement of ferromagnetism in δ-(Ga, Mn)As

Using density functional calculations, the mechanism of enhancement of exchange energy of δ-(Ga, Mn)As with shape deformation was elucidated. The initial Tc was 250 K with exchange energy 395 meV, thereafter Tc could be obtained as 308 K with a higher exchange energy when deformation was considered. Lattice constant variation in the z-direction (perpendicular to the Mn layer) had a significant effect on the exchange energy, while that in the x- or y-direction would not. Compared with pure GaAs, the anti-ferromagnetic (AFM) energy of δ-(Ga, Mn)As changed abnormally with shape deformation. Enhancement of this exchange energy could mainly be attributed to the high, narrow AFM t2g peak on the Fermi surface with shape deformation. These findings shed new light on the physics underpinning the design of dilute magnetic semiconductors with shape deformation for spintronic applications.