Defect-induced ferromagnetism in undoped and Mn-doped zirconia thin films

A doping-independent ferromagnetic hysteresis at 300 and 5 K was found for both undoped and Mn-doped zirconia thin films with up to 20 at. % Mn. The lack of Mn-induced magnetic ordering is a strong indication that the observed ferromagnetic effects are defect related. Electron paramagnetic resonance analysis supports the conclusion that Mn ions are in a magnetically ``silent'' state. Cubic ZrO₂:Mn films show a noticeable layer ferromagnetic saturation magnetization at 5 K, as compared to the monoclinic and tetragonal films, which clearly correlates with strain and a higher density of dislocations as the dominating microstructural defect.