X-ray analysis of wurtzite-type CoO(111) films on Ir(001): Correlation of structure, stress, electronic, and magnetic properties

We present a surface x-ray diffraction study in combination with stress experiments and ab initio calculations to investigate the structure and magnetic properties of 1.6 and 2.0 bilayer thick CoO(111) films grown on Ir(001). The CoO films grow in a wurtzite-like structure characterized by reduced distances between cobalt and oxygen atoms within one bilayer. The double-bilayer film is undertensile stress of +2.1 N/m which can be quantitatively attributed to epitaxial misfit and excludes the presence of significant Coulomb interactions. First-principles calculations reveal that the CoO films are metallic and that the magnetic order is noncollinear.