Professor Sung Wng Kim’s Research Team at the Department of Energy Science 

Successfully Develops New Magnetic Material Using Anionic Electrons

- Expects development and activation of magnetic materials with new principles

[Image 1] Professor Sung Wng Kim, Researcher Seung Yong Lee, Professor Jae-Yeol Hwang

Magnets are very important materials in everyday life, and they are applied to various fields such as hard disks and electric motors. In general, magnetic materials consist of alloys of expensive rare earth elements as the main components, but problems with the price burden and unstable supply of rare earth elements have raised the need for new magnetic materials.

Research on “electride” consisting of interstitial anionic electrons has drawn attention as a silver lining for the development of new magnetic materials that do not use rare earth elements, which were considered essential components for magnetic materials, or have significantly reduced their usage. The theoretical prediction that ferromagnetic characteristics can be expressed if interstitial anionic electrons exist independently in an empty space inside the material was reported, but no way to successfully synthesize new magnetic materials had been found.

The research team led by Professor Sung Wng Kim of the Department of Energy Science synthesized the world's first electride magnetic material with ferromagnetic properties and clearly discovered its principles.

Professor Sung Wng Kim’s team identified for the first time in the world the existence of interstitial anionic electrons that have their own magnetic moment, located independently in the empty spaces between two-dimensional layers (interlayer). The team also succeeded in developing a 2D (two-dimensional) electride magnetic material (Gd2C), which has ferromagnetism through a strong interaction (exchange interaction) between electrons and cations within its layers.

In particular, it is meaningful that the two-dimensional electride magnetic material (Gd2C) has stronger magnetic moments than conventional magnets made up of only rare earth elements (Gd) so that the application of electride materials enables the development of new magnetic materials with the same magnetic properties while reducing rare earth elements.

[Image 2]  A two-dimensional magnetic electride scheme. Anionic electrons located in empty spaces between layers interact with surrounding atoms with their own magnetic moments to show the ferromagnetism.

This study suggests that, unlike the general principle that the rare earth element expresses magnetism, it provides a new magnetic realization principle that the interstitial anion electrons have their own magnetic moment and express magnetic properties through interaction with surrounding atoms.

It is also expected to drive the study of magnetic electrides in a new direction since the results showed that the limitations of research on magnetic electride materials can be overcome and succeeded in the synthesis of an electride with ferromagnetism for the first time.

Using the new principle of how magnetism is shown in electride materials proposed by this study, it is expected that the use of expensive rare earth elements needed for the synthesis of magnetic materials will be reduced and the development of magnetic materials of electrides consisting of low-cost elements will be possible.

The findings were published on March 23rd in Nature Communications (IF 11.878), a world-renowned scientific journal. (https://www.nature.com/articles/s41467-020-15253-5)