[Back]

P. Haumer, P.L. Fulmek:
"Generalized two-dimensional Energetic Model of Ferromagnetic Hysteresis for Thin Film Material.";
Poster: 10th European Conference on Magnetic Sensors and Actuators (EMSA 2014), Wien; 07-06-2014 - 07-09-2014; in: "Book of Abstracts: 10th European Conference on Magnetic Sensors and Actuators", (2014), ISBN: 978-3-85465-021-8; 239.

In order to describe the anisotropic magnetic behavior of thin film material, a fully two-
dimensional (2D) framework is required. For this reason, a generalization of the one-
dimensional "Energetic Model of Ferromagnetic Hysteresis" (EM) [1] is presented. In this
context, the magnetic sample is considered as collection of elementary magnetic entities,
which can be grouped into several statistical domain classes and described by circular
statistical distribution functions. Based on the statistical distribution of the elementary
magnetic moments and the corresponding local energy terms, effects of temperature
dependent thermal excitations [2] or microscopic misalignments due to inhomogeneities [3]
have been investigated for thin Permalloy films.
In this work, the static magnetization process in the 2D formulation of the EM is presented,
focusing on the domain processes under consideration of classical pinning effects at defect
sites. Furthermore, in polycrystalline films local anisotropy variations of the individual grains
may cause a magnetic ripple structure, which gives reason for a significant remanence of the
hard-axis magnetization curve. In the stochastic 2D approach of the EM, such anisotropy
perturbations can be considered via additional domain classes in a self-consistent way.
The predictions of the model are compared to measured data obtained from a magneto-optical
Kerr measurement setup. Based on this comparison, the identified model parameters can be
related to the characteristics of the thin film production process (e.g. the distance between
target and substrate during the sputtering).
Finally, the main objective of the presented 2D energetic model is the relation of
microstructural properties of thin films to macroscopic magnetization curves. Together with
technological parameters, the results give at least a qualitative impression how to improve the
production (sputter) processes without performing expensive microscopic analyses for every
sample.