Status of Iron-Based Superconductors

Since the discovery of iron-based superconductors (IBSs) on LaFePO in 2006 [1], many types of IBSs have been fabricated. This plenary talk by Professor Kazumasa Iida presents an overview of IBS research and development in the last 18 years, involving characteristics of IBSs and strategies for increasing the superconducting transition temperature and critical current density.

IBSs have usually been compared to cuprates and MgB, and their research methodology has been implemented in IBSs. As a result, many similarities between IBSs and cuprates have been revealed, e.g., the parent compounds being antiferromagnets and grain boundaries being weak-links to some extent [2]. On the other hand, the distinct features of IBSs are highlighted as multiband superconductors (i.e., the five bands of Fe 3d orbital crossing the Fermi level) and extended s-wave symmetry.

Additionally, some of the IBSs are topological superconductors that can be possible platforms for quantum computing [3].

Finally, the history of research and development of IBSs is compared with that of the cuprates, and then future perspectives are discussed.

[1] Y. Kamihara, H. Hiramatsu, M. Hirano, R. Kawamura, H. Yanagi, T. Kamiya, H. Hosono, J. Am. Chem. Soc. 128, 10012 (2006).

[2] H. Hosono, A. Yamamoto, H. Hiramatsu, Y. Ma, Materials Today, 21, 278 (2018).

[3] P. Zhang et al., Science, 360, 182 (2018).

Dr. Kazumasa Iida is a full professor of Electrical and Electronic Engineering at Nihon University. He spent the University of Cambridge from 2004 to 2007 as a postdoctoral researcher under the supervision of Prof. David A Cardwell. After spending 3.5 years in Cambridge, he joined the group led by Prof. Bernhard Holzapfel at the IFW Dresden as a senior scientist.

He was appointed an associate professor at Nagoya University in 2014 and a full professor at Nihon University in 2022. His research experience covers a wide range of materials, involving the fabrication of Sr-ferrite magnets, the growth of garnet films for magneto-optical imaging, and the growth of HTS and Fe-based superconducting materials in bulk and thin films. He has published more than 200 peer-reviewed research papers. He is currently on the editorial board of Superconductivity.