Magnetic anisotropy and anomalous Hall effect of ultrathin Co/Pd bilayers

The magnetic properties and anomalous Hall effect of ultrathin Co/Pd bilayers have been studied. The easy magnetization axis of ultrathin Co/Pd bilayers switches from perpendicular-to-plane to in-plane if the Co film thickness increases. A temperature dependent reorientation transition of the easy axis occurs when the film thickness is close to this reorientation thickness. The anomalous Hall conductivity sigma(xy) and the longitudinal conductivity sigma(xx) have been evaluated taking into account the current density in each individual layer. The obtained values are consistent with previous investigations of thick Co films. The scattering independent mechanism seems to be the dominant source of the AHE effect in our samples. However, an interfacial contribution to the anomalous Hall conductivity which has opposite sign as compared with the bulk contribution is suggested by our data. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4764347]