The effect of interface anisotropy on demagnetization progress in perpendicularly oriented hard/soft exchange-coupled multilayers

Abstract

The demagnetization progress of various hard/soft multilayers with perpendicular crystalline anisotropy has been studied by a micromagnetic model, incorporating the effect of the interface anisotropy, which is evident on the nucleation field when the soft layer thickness is small. Both microscopic and macroscopic hysteresis loops as well as angular distributions for the magnetizations in the thickness direction have been calculated, taking into account of realistic values of the interface anisotropy. The formula for the nucleation field has been derived analytically, where the nucleation field increases linearly with the interface anisotropy for a wide thickness region. While the nucleation field could change by more than 90% due to the influence of the interface anisotropy, the interface anisotropy has no effect on the pinning field or the coercivity, but it has some slight influence on the angular distributions. On the other hand, positive interface anisotropy enhances the remanence and the energy products, whereas negative interface anisotropy deteriorates both of them. Comparison with the experimental data justifies our calculation, indicating that negative interface anisotropy should be avoided in the experiment.

A micromagnetic study: lateral size dependence of the macroscopic properties of rectangular parallelepiped Cobalt-ferrite nanoferromagnetic

“…Both of these fields had the same response to the material anisotropy. The material anisotropy induced an increase in the coercive field (Issa et al, 2013) as well as the nucleation field (Zhao et al, 2017). The result of this increase was the larger of the hysteresis curve, so that the dissipated energy was also getting higher (Salas-Solis et al, 2004).…”

Three- and two-dimensional calculations for the interface anisotropy dependence of magnetic properties of exchange-spring Nd2Fe14B/α-Fe multilayers with out-of-plane easy axes*

“…1, the calculation is performed only for a double-layer system because of the symmetry of the system. [30,31,37] An o-xyz coordinate system is established with the origin designed at the center of the interface. The easy axes of both layers denoted by e and the applied field are assumed to be in the z direction.…”

“…The hard layer thickness t h is set as 10 nm, while the soft layer thickness t s = 3 nm and 6 nm so that the calculated composite magnets are the exchange springs. [29][30][31] The above 3D energy could be simplified to a 1D expression, assuming all layers extending to infinity in the direction perpendicular to the z-axis, and the energy density per area in the film plane is [31,41] th /2…”

“…So far, there have been few studies on the influence of interface anisotropy on the magnetic properties of exchangespring magnets, which are all performed within a 1D micromagnetic framework. [29][30][31] A 3D micromagnetic calculation can give hysteresis loops, such as the nucleation field, coercivity, energy product, similar to the 1D model. It can also show the magnetic distributions within the film plane, which, however, cannot be described by the 1D model.…”

Influence of Material Parameters on the Stability of Artificial Skyrmion in Hard/Soft Magnetic Bilayers

“…Artificial skyrmion can only be obtained within a certain range K hard = 1 × 10 5 −4 × 10 5 J m −3 . The magnetic materials with strong magnetic anisotropy constant (such as rare‐earth magnetic materials like SmCo 5 (PMA constant of 5.00 × 10 5 J m −3 , saturation magnetization of 5.5 × 10 5 A m −1 , and exchange constant of 1.2 × 10 −11 J m −1 ) [ 24 ] is not suitable for the hard magnetic layer; the magnetic materials with magnetic anisotropy constant less than 100 kJ m −3 , such as Ni (PMA constant of 0.905 × 10 5 J m −3 , saturation magnetization of 4.93 × 10 5 A m −1 , and exchange constant of 0.92 × 10 −11 J m −1 ), [ 25 ] is also not suitable for preparing artificial skyrmions. Two types of skyrmions, namely the Néel‐type (Figure 1b) and the Bloch‐type (Figure 1c) skyrmion, can be formed in the hard/soft magnetic bilayers.…”