Breakthrough Iron-Based Magnetic Material Achieves Major Reduction in Core Loss

— Controlled Nanostructure and Magnetic Domains Open the Door to Next-Generation Transformers and EV Components —

2025.09.03

NIMS (National Institute for Materials Science)
Tohoku University
National Institute of Advanced Industrial Science and Technology (AIST)

A research team from NIMS, Tohoku University and AIST has developed a new technique for controlling the nanostructures and magnetic domain structures of iron-based soft amorphous ribbons, achieving more than a 50% reduction in core loss compared with the initial amorphous material. The developed material exhibits particularly high performance in the high-frequency range of several tens of kilohertz—required for next-generation, high-frequency transformers and EV drive power supply circuits. This breakthrough is expected to contribute to the advancement of these technologies, development of more energy-efficient electric machines and progress toward carbon neutrality. This research was published in Nature Communications on September 3, 2025.

Abstract

Background

Amid rapid growth in power consumption by AI-focused data centers, electric vehicles and other applications, efficient energy use has become a critical challenge. In power electronics—the technology that converts and supplies electricity—the performance of soft magnetic materials used in transformers, inductors and other components is key to improving their efficiency. Soft magnetic materials are metallic materials that respond quickly to external magnetic fields, and this fast response should be with minimum energy loss. However, as power electronics operate at increasingly higher frequencies, energy losses in these materials have grown, posing a serious efficiency challenge.

Key Findings

The joint research team recently developed a new technique for precisely controlling the nanostructures and magnetic domain structures inside iron-based soft amorphous ribbons. Using this technique, they achieveda reduction in core loss of more than 50% compared with the initial amorphous ribbons, particularly in the high-frequency range of up to several tens of kilohertz required for applications such as high-performance transformers and EV drive power supply circuits (Figure).

Figure. Schematic diagrams of the nanostructure and magnetic domain structure of a conventional amorphous soft magnetic ribbon (left) and the newly developed ribbon (right). The new material exhibits a controlled nanostructure and magnetic domain structure achieved using optimized thermal treatment. The central graph demonstrates that these structural controls reduce core loss by more than 50%.

Future Outlook

The research team plans to fabricate prototype devices such as transformers using the newly developed material and to test its integration into actual power conversion circuits.

Other Information

  • This project was carried out by a research team consisting of Ravi Gautam (Postdoctoral Researcher, Research Center for Magnetic and Spintronic Materials (CMSM), NIMS), Hiroaki Mamiya (Chief Researcher, CMSM, NIMS), Tadakatsu Ohkubo (Deputy Director, CMSM, NIMS), Hossein Sepehri-Amin (Group Leader, CMSM, NIMS), Nikita Kulesh (Research Fellow, International Center for Young Scientists, NIMS), Shozo Hiramoto (Researcher, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University (TU)), Satoshi Okamoto (Professor, IMRAM, TU), Nobuhisa Ono (PhD student, IMRAM, TU) and Takeshi Ogasawara (Senior Researcher, Core Electronics Technology Research Institute, AIST).
    This work was supported by the MEXT’s Innovative Power Electronics Technologies (INNOPEL) program (grant number: JPJ009777).
  • This research was published in Nature Communications, an open access journal, on September 3, 2025.

Published Paper

Title : Ultra-Low Core Loss in Fe-enriched Soft Magnetic Ribbons Enabled by Nanostructure and High-Frequency Domain Engineering
Authors : Ravi Gautam, Shozo Hiramoto, Nikita Kulesh, Hiroaki Mamiya, Satoshi Okamoto, Nobuhisa Ono, Takeshi Ogasawara, Tadakatsu Ohkubo, Hossein Sepehri-Amin
Journal : Nature Communications
DOI : 10.1038/s41467-025-63139-1
Publication Date : September 3, 2025

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Contact information

Regarding This Research

Hossein Sepehri-Amin
Group Leader, Green Magnetic Materials Group
Research Center for Magnetic and Spintronic Materials
National Institute for Materials Science
E-Mail: H.SEPEHRIAMIN=nims.go.jp (Please change "=" to "@")
TEL: +81-29-859-2739
Tadakatsu Ohkubo
Deputy Director, Research Center for Magnetic and Spintronic Materials
National Institute for Materials Science
E-Mail: OHKUBO.Tadakatsu=nims.go.jp (Please change "=" to "@")
TEL: +81-29-859-2716
Satoshi Okamoto
Professor
Institute of Multidisciplinary Research for Advanced Materials
Tohoku University
E-Mail: satoshi.okamoto.c1=tohoku.ac.jp (Please change "=" to "@")
TEL: +81-22-217-5357
URL: https://www2.tagen.tohoku.ac.jp/lab/okamoto/ (Okamoto Laboratory | Institute of Multidisciplinary Research for Advanced Materials) *Japanese
Takeshi Ogasawara
Senior Researcher, Correlated Electron Device Research Group
Core Electronics Technology Research Institute
National Institute of Advanced Industrial Science and Technology
E-Mail: t-ogasawara=aist.go.jp (Please change "=" to "@")
TEL: +81-50-3521-3045

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