UC Davis

We propose and investigate the properties of a digital ferromagnetic heterostructure consisting of a delta-doped layer of Mn in Si, using ab initio electronic-structure methods. We find that (i) ferromagnetic order of the Mn layer is energetically favorable relative to antiferromagnetic, and (ii) the heterostructure is a two-dimensional half-metallic system. The metallic behavior is contributed by three majority-spin bands originating from hybridized Mn-d and nearest-neighbor Si-p states, and the corresponding carriers are responsible for the ferromagnetic order in the Mn layer. The minority-spin channel has a calculated semiconducting gap of 0.25 eV. The band lineup is found to be favorable for retaining the half-metal character to near the Curie temperature. This kind of heterostructure may be of special interest for integration into mature Si technologies for spintronic applications.