Phys. Rev. Lett., 87,
267202 (2001)
Ab initio transport theory for digital ferromagnetic heterostructures
S. Sanvito, and Nicola A. Hill
We present a theoretical density functional study of the electronic, magnetic,
and transport properties of digital ferromagnetic heterostructures, obtained
by d doping GaAs with Mn. In the absence of intrinsic donors these systems
have a half metallic density of states, with an exchange interaction much
stronger than that of a random alloy with the same Mn concentration. Our
ab initio ballistic transport calculations show that the carriers at the
Fermi energy are strongly confined within a few monolayers around the MnAs
plane. This strong confinement is responsible for the large exchange coupling
and the two-dimensional half metallic behavior.