# Fileset

[ACSEM2025-Sepehri-Amin.docx](https://mdr.nims.go.jp/filesets/0896454b-0c7f-4b6e-8a63-fe2480e800fc/download)

## Creator

[SEPEHRI AMIN Hossein](https://orcid.org/0000-0002-7856-7897)

## Rights

[Creative Commons BY-NC Attribution-NonCommercial 4.0 International](https://creativecommons.org/licenses/by-nc/4.0/)

## Other metadata

[Development of magnetic materials for green energy conversions](https://mdr.nims.go.jp/datasets/cdab0b36-1ade-4607-838f-49c8b351a1a7)

## Fulltext

Development of magnetic materials for green energy conversionsPPH. Sepehri-AminNational Institute for Materials Science, Tsukuba, Japan h.sepehriamin@nims.go.jpMagnetic materials play a vital role in a wide range of applications, from energy conversion to data storage. Their functionality is largely determined by their magnetic hysteresis. For instance, large hysteresis is desired in permanent magnets and recording media, while minimizing hysteresis improves the performance of soft magnets and magnetocaloric materials. In this presentation, we will first provide an overview of our team’s work on tuning the hysteresis of various functional magnetic materials through material design and multi-length-scale microstructure engineering. In the first part, we demonstrate how introducing magnetoelastic anisotropy in soft magnetic materials can benefit reduction of core loss for high frequency power electronic applications. We will show that optimum annealing in Fe-based amorphous ribbons with a large magnetostriction induces a small stress-induced perpendicular magnetic anisotropy. This promotes change of magnetic domain configuration from large curvilinear magnetic domain to the formation of narrow stripe-shaped domain and resulted in a change in high frequency magnetization switching mechanism [1]. Unlike conventional approaches that focus on necessity of low magnetostriction values to reduce core loss, we succeeded in 50 % reduction of core loss even in materials with large magnetostriction which can open materials choice for high frequency power electronic applications. In the second part of this talk, we will highlight our efforts in developing on-demand permanent magnets with tailored properties—such as optimized electrical resistivity, improved thermal stability, flatter recoil curves, and reduced dependence on critical elements—while preserving excellent hard magnetic performance [2-4]. We will demonstrate how combinatorial research approach of advanced processing, multi-length-scale microstructure characterizations and magnetic domain observations, and digital twins of permanent magnets have enabled us in development of high coercivity Dy-free Nd-Fe-B magnets. Additionally, we will discuss how tailoring the magnetism of the thin intergranular phase can enhance the thermal stability of coercivity, bringing it closer to its theoretical limit—a key factor for high-temperature applications.References[1] R. Gautam et al. Nature Comm. 16 (2025) 8022.[2] J. S. Zhang et al. Acta Mater. 294 (2025) 121160.[3] Z. H. Kautsar et al. J. All. Comp. 1010 (2025) 177738.[4] J. Li et al. Science and Technology of Advanced Materials  22 (2021) 386.image1.jpeg