The influence of interface anisotropy on demagnetization progress and magnetic properties in parallelly oriented hard/soft exchange-coupled multilayers

Abstract

Abstract The effect of the interface anisotropy on the demagnetization progress and magnetic properties in Nd2Fe14B/α-Fe exchange-coupled multilayers with parallel crystalline anisotropy has been investigated within a micromagnetic framework. A set of equations satisfied by the angle between the magnetization and the applied field, as well as the formula for the nucleation field, have been derived analytically. The nucleation field goes up linearly with the interface anisotropy constants varying from −1 erg/cm2 to 1 erg/cm2 in a wide thickness range, with an amplitude up to 13%. The microscopic hysteresis loops, the evolution of the domain walls, the macroscopic demagnetization curves and the energy products are given by numerical calculations. The results indicate that the interface anisotropy affects not only the nucleation field and the maximal magnetic energy product, but also the pinning field or the coercivity. Positive interface anisotropy evidently enhances the pinning field or the coercivity, however, negative interface anisotropy obviously deteriorates the maximal energy product. These results suggest that a positive interface anisotropy should be preferred experimentally.