Structural and magnetic phase stability of Si/MnAs superlattices: Tetragonal-distortion-induced ferromagnetism and half-metallicity

초록

The structural and magnetic phase stabilities of a Si (001) MnAs superlattice have been investigated using the highly precise all-electron full-potential linearized augmented plane-wave method within the generalized gradient approximation. From a total energy and atomic force calculations, we found that the zincblende structure for MnAs is most stable over other atomic configurations, where either Mn or As layers are attached to the Si interface. The antiferromagnetic (AFM) coupling between the Mn atoms is calculated to be energetically favored over the ferromagnetic (FM) coupling by a total energy difference of 40 meVunit cell. More interestingly, we predict that a 2% tetragonal distortion from its AFM crystal structure induces a magnetic phase transition from the AFM to a half-metallic FM phase with a 0.36 eV band gap for the minority spin channel, which indicates a promising possible spintronics application. © 2004 American Institute of Physics.