Electronic structure and magnetic properties of delta-doped Mn in group IVB metal oxide

We study the Mn delta-doped group IVB metal oxides M(1-x)Mn(x)O(2) (M = Ti, Zr, Hf; x = 0.25, 0.167, 0.125) using density-functional theory calculations. We find that delta-doped rutile Ti(1-x)Mn(x)O(2) shows weak antiferromagnetism, while cubic Zr(1-x)Mn(x)O(2) and Hf(1-x)Mn(x)O(2) show robust half-metallicity. The pronounced half-metallicity up to room temperature, energetic preference for the existence of polarized face and compatibility with silicon indicate the potential spintronics application for delta-doped Zr(1-x)Mn(x)O(2) and Hf(1-x)Mn(x)O(2). We also investigate the effect of crystal structure and elements on the impurity induced magnetic properties via substituting Ti in Ti(1-x)Mn(x)O(2) with Zr (Hf), and Zr (Hf) in Zr(1-x)Mn(x)O(2) (Hf(1-x)Mn(x)O(2)) with Ti. Interestingly, we find that the crystal structures determine the ground states and properties around the Fermi energy (E(F)), while atomic species determine excitation states largely. That is, the magnetic properties are largely determined by the crystal structures.