Superconductivity is a phenomenon in which the electrical resistance of a material becomes zero at low temperatures. This is being applied to various fields, such as MRI, linear motor cars and quantum computers. However, the biggest drawback of its application in the real world is the low transition temperature. Since the discovery of cuprate superconductors, which have the highest transition temperatures at ambient pressure, several analogs have been explored. Nickel oxide superconductors, which were discovered in 2019, have also attracted considerable attention owing to their similarity with copper oxides, and there is an active search to discover materials with higher transition temperatures by investigating the type of substrate and pressure.
A research group led by Assistant Professor Motoharu Kitatani of the Graduate School of Science at the University of Hyogo (visiting researcher at the RIKEN Center for Emergent Matter Science), Professor Ryotaro Arita of the Research Center for Advanced Science and Technology at the University of Tokyo (team leader at the RIKEN Center for Emergent Matter Science) and Professor Karsten Held of TU Wien has used state‐of‐the‐art computational methods to describe the superconducting phase diagram of copper oxides and nickel oxides and investigated the possibility of optimizing their transition temperatures by performing comprehensive calculations for a wide range of model parameters. The spatial extension of the dynamical mean‐field theory allows us to precisely account for the effects of strong interactions between electrons. As a result, the research group succeeded in appropriately explaining recent experimental results that indicated an increase in transition temperature due to pressurization and in deriving the optimal conditions. Combining these results with first‐principles calculations, they showed that the transition temperature could be improved in layered palladium oxides with a similar structure and predicted their phase diagram. Their research results were published in Physical Review Letters.
These results enable the development of a new group of high‐temperature superconducting materials and are expected to be a step toward the realization of linear motor cars and lossless electricity storage. Furthermore, through comparison with high‐temperature superconductors discovered thus far, such as cuprates, these results are expected to make significant progress in understanding the expression mechanism of superconductivity and measures to improve the transition temperature of superconductors.
Publication: Physical Review Letters
Title: Optimizing Superconductivity: From Cuprates via Nickelates to Palladates
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