We have comprehensively searched for new superconductors in the antiperovskite transition metal pnictides AnM3X (A = alkali metals, alkaline earth metals, rare earths; M = transition metals; X = pnictogen; n = 1 or 2), a material system that remains underexplored. As a result, we have discovered a variety of new antiperovskites including following superconductors. Mg2Rh3P exhibits superconductivity at 3.8 K by introducing about 5 mol% Mg deficiency (Fig. 1a) [1]. Although non-centrosymmetric (NCS) antiperovskites of CaPd3P and SrPd3P are non-superconducting, a centrosymmetric (CS) phase appeared in their solid solution (Ca,Sr)Pd3P exhibits superconductivity at 3.5 K [2,3]. Partial substitution of Pt into SrPd3As results in the appearance of superconductivity at 3.7 K associated with a structural phase transition (Fig. 1b) [5]. LaPd3P with a new prototype NCS cubic structure exhibits a superconductivity at 0.38 K (Fig. 1c) [4]. Thus, the antiperovskite transition metal pnictide is a promising material system that still has room to explore new superconductors.
[1] A. Iyo et al, Phys. Rev. Materials 3, 124802 (2019).
[2] A. Iyo et al, Inorg. Chem., 59, 12397 (2020).
[3] I. Hase et al, J. Phys.: Conf. Ser.1975, 012004 (2021).
[4] A. Iyo et al, Inorg. Chem.,60, 18017 (2021).
[5] A. Iyo et al, Inorg. Chem., 61, 12149 (2022).
This study was supported by the Japan Society for the Promotion of Science (JSPS) Grants-in-Aid for Scientific Research (KAKENHI) (22K04193).
Figure 1 (a) Crystal structure of Mg2Rh3P (Mo3Al2C type, P4132), (b) Phase diagram of Sr(Pd,Pt)3As, (c) Crystal structure of LaPd3P (new prototype, I-43m).
Keywords: new superconductor, antiperovskite, transition metal pnictide, Mg2Rh3P, (Ca,Sr)Pd3P, Sr(Pd,Pt)3As, LaPd3P