Improvement of critical current density of BaCuO by increase in configurational entropy of mixing.

BaCuO (123, : rare earth) is one of the high-temperature superconductors with a transition temperature ( ) exceeding 90 K. Because of its high- and large critical current density ( ) under magnetic fields, 123 superconductors have been expected to play a key role in superconductivity application. To accelerate application researches on 123-based devices, further improvements of characteristics have been desired. In this study, we investigated the effects of high-entropy alloying at the site on the superconducting properties, through the measurements of local (intra-grain) ( ) by a remanent magnetization method. We found that shows a trend to be improved when four or five elements are mixed at the site, which results in high configurational entropy of mixing (Δ ). All samples exhibited an order of few MA cm which is a criterion for practical application and the highest resulted in a value of around 7.0 MA cm at = 2.0 K. Because high-entropy alloying can improve of 123 superconductors, our entropy-engineering strategy introduced here would be useful for the development of 123 superconducting materials available under high magnetic fields.