Tuning perpendicular magnetic anisotropy in the MgO/CoFeB/Ta thin films

Understanding the magnetic anisotropy at ferromagnetic metal/oxide interface is a fundamental and intriguing subject. Here we propose an approach to manipulate the strength of perpendicular magnetic anisotropy (PMA) by varying MgO thickness in the MgO/CoFeB/Ta thin films. We identify that the PMA at the MgO/CoFeB interface is tuned by the crystalline structure of bulk MgO layer and decreases dramatically due to the onset of crystalline MgO forming with the increase of MgO thickness. Our work opens an avenue to manipulate the magnetic anisotropy by the modification of the ferromagnetic metal/oxide interface.