Abstract A three-dimensional continuum based micromagnetic model is developed to simulate the magnetization process in polycrystalline thin films and address the influence of crystallographic texturing, grain size and the substrate-induced strain on the spontaneous domain structure and hysteresis curves of NiFe2O4 and CoFe2O4 thin films. The model employs the Landau–Lifshitz–Gilbert equation along with mechanical equilibrium and Gauss' Law for magnetism to calculate the temporal and spatial distributions of the magnetic moments. Thus, this approach falls within the category of phase-field methods used for non-conserved systems. The finite element method is used to solve the partial differential equations in fully coupled fashion while using a different discretization method for each equation. The results demonstrate how the magnetization process is altered by adopting different microstructural orientations revealing stronger sensitivity in CoFe2O4 thin films than in NiFe2O4 thin films. Moreover, it is shown that the substrate-induced compressive strain favors in-plane magnetization, whereas the tensile strain switches the easy axis from the in-plane to the out-of-plane direction. The validity of the model is verified by comparing the results with recently published experimental data for sol-gel deposited NiFe2O4 thin films.

中文翻译：

---

NiFe 2 O 4 和CoFe 2 O 4 薄膜中晶体织构和衬底诱导应变效应的微磁分析

摘要 开发了一种基于三维连续介质的微磁模型来模拟多晶薄膜的磁化过程，并解决晶体结构、晶粒尺寸和衬底诱导应变对 NiFe2O4 和 CoFe2O4 薄膜的自发畴结构和磁滞曲线的影响。 . 该模型采用 Landau-Lifshitz-Gilbert 方程以及机械平衡和高斯磁定律来计算磁矩的时间和空间分布。因此，这种方法属于用于非守恒系统的相场方法的范畴。有限元方法用于以完全耦合的方式求解偏微分方程，同时对每个方程使用不同的离散化方法。结果证明了磁化过程如何通过采用不同的微观结构取向来改变，这表明 CoFe2O4 薄膜比 NiFe2O4 薄膜具有更强的敏感性。此外，结果表明，衬底诱导的压缩应变有利于面内磁化，而拉伸应变将易轴从面内切换到面外方向。通过将结果与最近公布的溶胶-凝胶沉积 NiFe2O4 薄膜的实验数据进行比较，验证了模型的有效性。而拉伸应变将易轴从平面内切换到平面外方向。通过将结果与最近公布的溶胶-凝胶沉积 NiFe2O4 薄膜的实验数据进行比较，验证了模型的有效性。而拉伸应变将易轴从平面内切换到平面外方向。通过将结果与最近公布的溶胶-凝胶沉积 NiFe2O4 薄膜的实验数据进行比较，验证了模型的有效性。