Materials discovery for iron-based superconductivity*

Iron with a large magnetic moment was widely believed to be harmful to the emergence of superconductivity because of the competition between the static ordering of electron spins and the dynamic formation of electron pairs. Thus, the discovery of high Tc iron-based superconductors (IBSCs) in 2008[1] rekindled extensive study globally. As a result,IBSCs have since grown to become a new class of high critical temperature (Tc) superconductors next to the high-Tc cuprates. The rapid research progress in the science and technology of IBSCs over the past decade has resulted in a vast amount of knowledge on IBSC materials and mechanisms with the publication of more than several tens of thousands of papers and several monographs + a comprehensive review. [2,3] Recent progress in the technical applications (bulk magnets, thin films, and wires) of IBSCs is also remarkable. Highlights of their applications include high-field bulk magnets workable at 15–25 K, thin films with high critical current density (Jc) > 1 MA/cm² at ~10 T and 4 K, and an average Jc of 1.3×10⁴ A/cm² at 10 T and 4 K achieved for a 100-m-class-length wire[3]. These properties also make IBSCs promising for applications using high magnetic fields. Here I’d like to talk on how IBSCs were discovered and the progress in materials of IBSCs to date[3-5].

[1] Kamihara, Watanabe, Hirano, Hosono, J.Am.Chem.Soc.130,3296(2008)
[2]Wang,Hosono, Dai, Iron-based Superconductors, Pan Stanford(2013); Johnson, Xu, Yin, Iron-based Superconductors Springer (2015); Johnston, Adv.Phys.59,803(2010).
[3] (Recent Review)Hosono, Yamamoto, Hiramatsu, Ma, Materials Today, in press 10.1016/j-mattod.2017.09.006, [4] (Recent Review) Hosono and Kuroki, Physics C514,399(2015), [5] Hosono et al. Sci. Technol. Adv. Mater. 16 (2015) 033503-1-87 (2015)