Martinez-Casado R, Dasmahapatra A, Sgroi M F, Romero-Muñiz C, Herper Heike C, Vekilova Olga Yu, Ferrari A M, Pullini D, Desmarais J, Maschio L
Department of Materials Physics, Faculty of Physical Sciences, University Complutense Madrid, 28040, Madrid, Spain. University of Torino, Dipartimento di Chimica, via P. Giuria 5, I-10125 Turin, Italy.
J Phys Condens Matter. 2019 Dec 18;31(50):505505. doi: 10.1088/1361-648X/ab4096.
High-performance permanent magnets (PM) are compounds with outstanding intrinsic magnetic properties. Most PMs are obtained from a favorable combination of rare earth metals (RE = Nd, Pr, Ce) with transition metals (TM = Fe, Co). Amongst them, CeFeTi claims considerable attention due to its large Curie temperature, saturation magnetization, and significant magnetocrystalline anisotropic energy. CeFeTi has several potential applications, in particular, in the development of electric motors for future automatic electrification. In this work, we shed some light on the mictrostructure of this compound by performing periodic hybrid-exchange density functional theory (DFT) calculations. We use a combined approach of atom-centered local orbitals, plane waves and full-potential linear muffin-tin orbital (LMTO) for our computations. The electronic configuration of the atoms involved in different steps of formation of the crystal structure of CeFeTi gives an explanation on the effect of Ce and Ti on its magnetic properties. While Ti stabilizes the structure, atomic orbitals of Ce hybridizes with Fe atomic orbitals to a significant extent and alters the electronic bands. Our calculations confirm a valence of 3 for Ce, which has been deemed crucial to obtain a large magnetocrystalline anisotropy. In addition, we analyze several spin configurations, with the ferromagnetic configuration being most stable. We compare and contrast our data to those available and provide an insight for further development of optimized high-performance PMs. Moreover, we compute the Magnetocrystalline Anisotropy of this compound by means of two approaches: the Force Theorem and a full-potential LMTO method.
高性能永磁体（PM）是具有出色固有磁性能的化合物。大多数永磁体是由稀土金属（RE = Nd、Pr、Ce）与过渡金属（TM = Fe、Co）的良好组合获得的。其中，CeFeTi因其高居里温度、饱和磁化强度和显著的磁晶各向异性能而备受关注。CeFeTi有多种潜在应用，特别是在未来自动电气化的电动机开发方面。在这项工作中，我们通过进行周期性混合交换密度泛函理论（DFT）计算，对该化合物的微观结构进行了一些研究。我们在计算中使用了以原子为中心的局域轨道、平面波和全势线性 muffin-tin 轨道（LMTO）的组合方法。参与CeFeTi晶体结构形成不同步骤的原子的电子构型，解释了Ce和Ti对其磁性能的影响。虽然Ti使结构稳定，但Ce的原子轨道与Fe的原子轨道在很大程度上发生杂化，改变了电子能带。我们的计算证实Ce的化合价为3，这被认为对获得大的磁晶各向异性至关重要。此外，我们分析了几种自旋构型，其中铁磁构型最稳定。我们将我们的数据与现有数据进行比较和对比，并为优化高性能永磁体的进一步发展提供见解。此外，我们通过两种方法计算了该化合物的磁晶各向异性：力定理和全势LMTO方法。
