Epitaxial growth of Co2Cr0.6Fe0.4AlCo2Cr0.6Fe0.4Al Heusler alloy thin films on MgO (0 0 1) substrates by magnetron sputtering

We demonstrate that single-crystalline epitaxial films of the Heusler alloy Co2Cr0.6Fe0.4AlCo2Cr0.6Fe0.4Al (CCFA) featuring excellent surface flatness can be grown on MgO (0 0 1) substrates by magnetron sputtering deposition at room temperature and subsequent annealing at high temperatures. X-ray pole figure measurements reveal that the films exhibit the B2-type structure and the [1 0 0] direction of the films is rotated by 45° from the [1 0 0] direction of the MgO substrate. Moreover, their Curie temperatures and saturation magnetizations are also improved by annealing. The surface roughness is about 0.2 nm rms according to atomic force microscopy.