Micromagnetic analysis of the effect of the easy axis orientation on demagnetization process in Nd2Fe14B/α-Fe bilayers

Abstract

The hysteresis loops and energy products in the magnetization reversal process are investigated by one-and three-dimensional micromagnetic methods for a Nd2Fe14B/α-Fe bilayer system with an angle β between the applied field and the easy axis, and the results are compared with available experimental results. The calculation shows that the deviation of the easy axis affects the magnetization reversal process seriously. When β≠0°, there is no obvious nucleation in the magnetization reversal process. The remanence decreases as β decreases, and the squareness of the hysteresis loops is weakened, leading to the sharp decrease of energy product. For Nd2Fe14B(10 nm)/α-Fe(8 nm), the energy product decreases by 30.3% when β=10°. In the magnetization reversal process, as the total energy reaches the maxium, Zeeman energy decreases with increasing of β, and the exchange energy first increases and then decreases slightly, and the anisotropic energy increases with the increasing of β. The deviation of easy axis has a greater influence on the energy product of the bilayer system with larger soft thickness. The out-of-plane deviation of easy axis has a similar effect.