Using first principles calculation, we investigated the magnetic anisotropy of Pd/Co/Pd ultrathin film. Here, we
explored the magnetic anisotropy of pristine Pd/Co/Pd ultrathin film and also interface vacancy defect (Pd or
Co) and the oxygen diffusion as well. No substantial change in the magnetic moment is found in the vacancy
defect and also in the O diffusion structure relative to the pristine system. We found that the pristine Pd/Co/Pd
system has a perpendicular magnetic anisotropy of 1.37 meV/cell. This perpendicular magnetic anisotropy
decreased to 0.46 meV/cell in Pd vacancy defect and it became 0.56 meV/cell in Co vacancy defect. We also
obtained similar magnetic anisotropy energy of 0.52 meV/cell in the O impurity system. Although the vacancy
defect and O impurity system exhibited a similar magnetic anisotropy, we found that this feature originated
from different spin-orbit coupling effect which is sensitive to the sample preparation condition.