Solid state chemistry of superconducting transition-metal oxides
Author: Shimakawa, Yuichi
Affiliation: Kyoto University
Type: Invited Talk
Session: Materials design and discovery
Date and Time: 21.07.2026, 11:45 - 12:15
Recently, superconductivity in nickel oxides has attracted much attention. The discovery of superconductivity in epitaxially strained thin-film samples was a breakthrough. Subsequent discoveries of bulk superconductivity under pressure in Ruddlesden-Popper phases have expanded research on this class of materials. Superconductivity emerges through carrier doping into square-planar Ni1+O₂ layers in thin films. In bulk Ruddlesden-Popper phases, on the other hand, it appears to be achieved in doped Ni2+O6 octahedral layers. To understand the nature of superconductivity in nickel oxides, it is indispensable to clarify fundamental material characteristics, such as layer order and oxygen nonstoichiometry. It is also interesting to compare the crystal and electronic structures between nickelate and cuprate superconductors. In this presentation an overview of the synthesis conditions and structural features of superconducting transition-metal oxides are provided. The results of attempts to stabilize the square-planar TMO₂ planes by reduction and the TMO₆ octahedra by oxidation are also presented.