Magnetic properties of [(CoP)soft/(NiP)am/(CoP)hard/(NiP)am]n superlattices

https://doi.org/10.1016/j.physb.2024.416664

We report on the results of experimental and theoretical studies of magnetic superlattices [(CoP)_soft/(NiP)_am/(CoP)_hard/(NiP)_am]_n (n = 1, 5, 10, 15, 20, 40, t_CoP = 5 nm, t_NiP = 2 nm) produced by electroless deposition method. Cross-section electron microscopy image shows the layers do not mix and the interfaces between the layers are not blurred. We found the behavior of the magnetic hysteresis loops is similar to the exchange spring. Three peaks of microwave absorption are observed in the electron magnetic resonance spectra. To explain this, a model of a three-sublattice magnet with long-range interlayer interaction due to magnetic proximity effect is proposed. A perpendicular magnetic anisotropy is formed at the interface between the magnetic and non-magnetic layers. The interlayer interaction between the nearest magnetically soft and hard (J₁) layers is found to be negative, the interaction between magnetically soft layers (J₂) is positive, while J₁ is about an order of magnitude greater than J₂.