1996 年 20 巻 S_1_MORIS_96 号 p. S1_223-228
Micromagnetic finite element calculations rigorously describe the effects of microstructural features on the magnetic properties of Co/Pt multilayer thin films. Within the framework of static micromagnetism, the hysteresis properties result from subsequent minimum energy solutions for decreasing or increasing applied fields. The concurrent modelling of inhomogeneous magnetic states within the individual grains and of co-operative reversal processes leads to a large-scale optimisation problem. In order to reduce the number of variables, shell elements which account for the multilayer structure and a magnetic vector potential to treat the long-range stray fields are used. Micromagnetic calculations of demagnetisation curves and domain structures in Co/Pt multilayer systems show a qualitative agreement with experimental data obtained from Lorentz electron microscopy. The nucleation field of Co/Pt multilayer increases with improving texture. Spatial fluctuations of the anisotropy directions from grain to grain create barriers for domain wall motion. The pinning field increases with increasing grain size. The coercive squareness improves with decreasing number of bilayers. The ac-demagnetised state shows a maze-like structure. The underlying skeleton shape of the domain structure remains substantially unchanged under an applied field. The transition width and the domain wall jaggedness increase with decreasing quality of texture and increasing grain size.
