Insights into the local electronic structure of semiconducting boron carbides in the vicinity of transition metal dopants

Based on the experimentally determined pairwise site locations of transition metal atoms in doped semiconducting boron carbides, model spin-polarized electronic structure calculations indicate that some transition metal doped semiconducting boron carbides may act as excellent spin filters when used as the dielectric barrier in a magnetic tunnel junction structure. The local spin configuration of all the 3d transition metals, Ti to Cu, doped boron carbides are compared using first-principle total energy calculations on cluster and infinite icosahedral chain models. In the case of Ti and Fe doping, there may be considerable enhancements in the magneto-resistance of the heterostructure. The models also confirm that the favorable sites 3d transition metal atoms occupied are within the icosahedral cage, in a pairwise fashion on adjacent icosahedra.