Effect of interface on magnetic properties of Co_(20)Fe_(60)B_(20) in ion-beam sputtered Si/CoFeB/MgO and Si/MgO/CoFeB bilayers

摘要

Effect of interface on magnetic properties of Co_(20)Fe_(60)B_(20) in ion-beam sputtered Si/MgO/CoFeB(top) and Si/CoFeB(bottom)/MgO bilayers is reported. The X-ray reflectivity and magneto-optical Kerr effect analysis revealed that, the interface between bottom MgO and top CoFeB is sensitive to the MgO growth process (post-oxidation, ion-assisted and reactive growth) and its process parameters (assist-ion energy). An increase in interface width from 0.17 nm to 0.47 nm correlates to increase in coercivity from 6 Oe to 34 Oe, decrease of in-plane uniaxial magnetic anisotropy (UMA) from 8×10~3 to 5×10~3J/m~3 and changes in magnetization reversal. In contrast, the CoFeB(bottom)/MgO interface shows different magnetic behavior and no UMA.