Perpendicular magnetic anisotropy and the magnetization process in CoFeB/Pd multilayer films

The perpendicular magnetic anisotropy (PMA) and dynamic magnetization-reversal process in [CoFeB t nm/Pd 1.0 nm](n)( t = 0.4, 0.6, 0.8, 1.0 and 1.2 nm; n = 2 - 20) multilayer films have been studied by means of magnetic hysteresis and Kerr effect measurements. Strong and controllable PMA with an effective uniaxial anisotropy up to 7.7 x 10(6) Jm(-3) and a saturation magnetization as low as 200 emu cm(-3) are achieved. The surface/interfacial anisotropy of the CoFeB/Pd interfaces-the main contribution to the PMA-is separated from the effective uniaxial anisotropy of the films and appears to increase with the number of CoFeB/Pd bilayers. Observation of the magnetic domains during a magnetization-reversal process, using polar magneto-optical Kerr microscopy, reveals the detailed behavior of the nucleation and displacement of the domain walls.