Digital Ferromagnetic Heterostructure Composed of Mn in Si*

We examine the electronic and magnetic properties of digital ferromagnetic heterostructures (DFH) composed of Mn atoms confined in a layer of Si by using an \textit{ab-initio} algorithm. The $\delta $-layer can have the composition of Mn$_{1-x}$Si$_{x}$ with x=0 for 1ML, x=0.5 for 0.5ML, and x=0.75 for 0.25ML coverage of Mn. Each DFH is simulated by a tetragonal supercell formed by stacking 8 cubes of the Si crystal in the [100] direction. For each supercell, the value of x determines the area of the plane perpendicular to the [100] direction. For all cases, the total energy difference between the ferro- and antiferro-magnetic phases, the magnetic moments for the ferromagnetic phase, and the density of states at the Fermi energy as functions of x will be presented.