Anomalous Hall Effect Behavior In (100) And (110) Cro2 Thin Films

First and second order magnetic anisotropy constants have been determined in (110) and (100) CrO2 films using magnetometry and anomalous Hall effect measurements. Higher in-plane anisotropy is observed in strain-free (110) CrO2 films as compared to strained (100) CrO2 films, while out-of-plane magnetic anisotropy (OPMA) is stronger in (100) films. Temperature-dependent OPMA is particularly striking for (110) films with a sharp drop below 200 K, whereas for (100) films the anisotropy increases as the temperature decreases. These results are consistent with changes in the magnetization orientation with decreasing temperature, possibly caused by differences in the thermal expansion coefficient between the substrate and film. (C) 2011 American Institute of Physics. [doi:10.1063/1.3583568]