Abstract
We have studied the variation of perpendicular magnetic anisotropy (PMA) of CoFeB layers with the oxidation degree of the MgO buffer layers. After annealing at 330 °C, the out-of-plane anisotropy field (H k ) of 1.5-nm CoFeB could be optimized to 3.1 kOe. To investigate the orbital hybridization of the Fe-3d and O-2p, the orbital moments per hole (m orb /N h ) of Fe in annealed CoFeB layers were extracted by using x-ray magnetic circular dichroism. The dependence of m orb / N h on the oxidation time of MgO coincided with that of H k , which revealed that PMA of annealed CoFeB originated from the interfacial orbital hybridization. © 2012 American Institute of Physics.