Correlation between microstructure at fine scale and magnetic properties of magnetoresistive Cu80Fe10Ni10 ribbons: Modeling of magnetization

Due to the complexity of granular magnetic systems microstructure, the relation between the magnetic and transport properties and the microstructure is not fully understood yet.Through the use of several characterization techniques, the structure of Cu80Fe10Ni10 ribbons was observed at several scales from the microscopic to atomic scale. Our measured structural parameters by these techniques were used in order to model the magnetic properties. By using a model derived from the superparamagnetic approach, the structural parameters can be directly related to the magnetization of nanogranular systems. Thus, using this model, many studies have determined structural parameters such as average size of precipitates, their average magnetic moment and the number density of precipitates. However, when these parameters are determined experimentally using structural characterization techniques, differences are observed between experimental data, and data derived from models using the Langevin curves. These differences are often attributed to the presence of interactions that alter the overall magnetization and are not considered in this model. Recently a model describing the contribution of interactions to the magnetization has been developed. This model allows the calculation of structural data such as the magnetic moment of particles or the number density of particles.Here structural data will be compared with experimental data determined using these two models. We show that these adjustments indicate the limits of the Langevin model when applied to a system where the magnetic interactions are not negligible. An adjustment taking into account the paramagnetic contribution of the matrix gives results much closer to those obtained by structural characterization. Finally, to improve the fit, the model must take into account interactions between particles.

► Modeling of magnetization of the nanogranular magnetic ribbons is presented.
► The Langevin model is not adapted to granular systems.
► Interparticle interaction and the paramagnetic matrix contributions are essential.
► These models have given better fit in agreement with structural characterization.