Growth, structural, and magnetic properties of single-crystal full-Heusler Co2TiGe thin films

This work presents the growth, structural characterization, and measurement of magnetic properties of Co2TiGe thin films grown by molecular beam epitaxy on insulating MgO (001) substrates and conductive lattice matched InAlAs/InGaAs/InAlAs epitaxial layers grown on n-InP (001) substrates. A GdAs diffusion barrier was used to minimize interfacial reactions during Co2TiGe growth on InAlAs. The surface morphology, structural quality, and magnetic behavior were examined by reflection high-energy electron diffraction, scanning tunneling microscopy, X-ray diffraction, and superconducting quantum interference device magnetometry. The results reveal high quality Co2TiGe thin films with a saturation magnetization of ∼1.8 μB/formula unit and a Curie temperature of ∼375 K. The magnetic easy axis was found to lie in the [110] direction but magnetometry also reveals that there is only a small difference in energy between the [110] and [010] magnetization directions.