Epitaxial films of Heusler compound Co2FeAl0.5Si0.5 with high crystalline quality grown by off-axis sputtering

Co2FeAl0.5Si0.5 films with a surface roughness of 0.12 nm have been grown epitaxially on lattice-matched MgAl2O4 (001) substrates by off-axis sputtering. X-ray diffraction shows pronounced Laue oscillations, rocking curves as narrow as 0.0043°, and clear Co2FeAl0.5Si0.5 (111) peaks indicating L21 ordering. Magnetic characterizations show a clear magnetocrystalline anisotropy comprising cubic and epitaxy-induced uniaxial terms. Nuclear magnetic resonance measurements reveal L21 order of 81% in the Co2FeAl0.5Si0.5 films. Magnetotransport measurements show a distinct separation of anisotropic magnetoresistance and ordinary magnetoresistance. These results demonstrate the state-of-the-art crystalline quality and magnetic uniformity of the Co2FeAl0.5Si0.5 films.