Fachgruppe Nanostrukturierte Materialien    

The influence of mild thermal annealing and nickel addition on the magnetic properties of Co–CoO multilayers is investigated. Co–CoO and CoNi–CoNiO multilayers were fabricated by radio-frequency magnetron sputtering and natural oxidation. Their magnetic properties have been studied via the magneto-optical Kerr effect and a vector network analyzer ferromagnetic resonance setup. The Co–CoO multilayers were annealed up to 90min at 250C and they were found to be always in-plane magnetized. The value of Gilbert damping was evaluated. The multilayers after annealing or Ni addition show a small increase in coercivity without considerable changes in their anisotropy. The phenomenon of inverted hysteresis with negative remanence, with the field being applied perpendicular to the film plane, has been recorded. It was modeled with two coexisting magnetic moments with in-plane and perpendicular anisotropies, respectively