Epitaxial Growth of Full-Heusler Alloy Co$_2$MnSi Thin Films on MgO-Buffered MgO Substrates

Full-Heusler alloy Co₂MnSi (CMS) thin films were epitaxially grown on MgO-buffered MgO substrates through magnetron sputtering. The films were deposited at room temperature and subsequently annealed in situ at 600degC. X-ray pole figure measurements of the annealed films showed 111 peaks with fourfold symmetry, providing direct evidence that these films were epitaxial and crystallized in the L2₁ structure. The annealed films had sufficiently flat surface morphologies with root-mean-square roughness of about 0.22 nm at a film thickness of 50 nm. The saturation magnetization of the annealed films was 4.5mu_B/f.u. at 10 K, corresponding to about 90% of the Slater-Pauling value for CMS