[PCP1] Physics and Chemistry1

[PCP1-08] Enhancement of T_c in Na-substituted BaBi₃ with AuCu₃-type

*Terunari Koshinuma¹, Yoshihisa Kamiya¹, Hiroshi Fujihisa², Yoshito Gotoh², Izumi Hase², Shigeyuki Ishida², Hiraku Ogino², Hiroshi Eisaki², Kenji Kawashima¹, Akira Iyo² (1. IMRA JAPAN Co., Ltd. (Japan), 2. National Institute of Advanced Industrial Science and Technology (Japan))

Keywords:

New superconductor,AuCu3-type

We have been verifying the effectiveness of applying the concept of combinatorial chemistry (CC) to the exploration of superconducting materials through bulk inorganic synthesis. A key feature of CC-based exploration is synthesizing samples containing a wide variety of elemental combinations in a single process (combinatorial synthesis) and rapidly identifying compounds with the target properties via high-throughput screening. In conventional solid-state reactions, starting materials are homogeneously mixed and heated for a long time (typically several days) to promote ionic diffusion and form compounds. In contrast, in this study, heterogeneous mixing of multiple elements followed by intentionally short-time heating (a few minutes) yields mixtures comprising a large number of possible compounds. For the evaluation of superconducting phases, the pronounced magnetic response associated with superconducting transitions can be detected even when the volume fraction is as low as 0.01%. Thus, high-throughput screening can be performed by measuring the temperature dependence of magnetization using a highly sensitive SQUID magnetometer.As a demonstration of this concept, our group has previously discovered new superconductors [1-7]. Furthermore, when combined with high-pressure synthesis, this approach is expected not only to stabilize crystal structures that are unstable or metastable at ambient pressure but also to allow the handling of highly volatile or reactive elements. Using these approaches, we have further explored related compounds and identified a new superconductor (Ba,Na)Bi₃ (T_c = 8.4 K), obtained by partial substitution of Ba in AuCu₃-type BaBi₃ (T_c = 5.8 K) [8]. Substitution of Na⁺ for Ba²⁺ introduces hole carrier and suggests enhancement of density of state at the Fermi energy level, which is important component of T_c in BCS theory.In this presentation, we will report the sample synthesis method, parameters of the normal and superconducting states, and the electronic band structure obtained by first-principles calculations.[1] A. Iyo et al., Sci Rep 5, 10089 (2015). [2] T. Kinjo et al., Supercond. Sci. Technol. 29 03LT02 (2016). [3] A. Iyo et al., Phys. Rev. Materials 3, 124802 (2019). [4] A. Iyo et al., Inorg. Chem. 59, 12397 (2020). [5] A. Iyo et al., Inorg. Chem., 61, 12149 (2022).[6] T. Koshinuma et al., Intermetallics 148, 107643 (2022). [7] T. Koshinuma et al., Intermetallics 181, 108748 (2025).[8] N. Haldolaarachchige et al., Supercond. Sci. Technol. 27 105001 (2014).