Hidden Structural and Superconducting Phase Induced in Antiperovskite Arsenide SrPd$_{3}$As

TL;DR

This study reports the discovery of a new antiperovskite arsenide SrPd3As and reveals hidden structural and superconducting phases in Sr(Pd1-xPtx)3As, highlighting the role of elemental substitution in uncovering novel material properties.

Contribution

First identification of antiperovskite arsenide SrPd3As and characterization of hidden structural and superconducting phases induced by Pt substitution.

Findings

SrPd3As has a non-centrosymmetric tetragonal structure.

Superconductivity up to 3.7 K observed in Sr(Pd1-xPtx)3As with 0.3 ≤ x ≤ 0.7.

Phase diagram shows superconductivity in centrosymmetric phases induced from non-centrosymmetric phases.

Abstract

Enriching the material variation often contributes to the progress of materials science. We have discovered for the first time antiperovskite arsenide SrPd$_{3}$As and revealed a hidden structural and superconducting phase in Sr(Pd$_{1-x}$Pt$_{x}$)$_{3}$As. The Pd-rich samples (0 $\leq$ x $\leq$ 0.2) had the same non-centrosymmetric (NCS) tetragonal structure (a space group of $I41md$) as SrPd$_{3}$P. For the samples with 0.3 $\leq$ x $\leq$ 0.7, a centrosymmetric (CS) tetragonal structure ($P4/nmm$) identical to that of SrPt$_{3}$P was found to appear, accompanied by superconductivity at a transition temperature ($T_\mathrm{c}$) up to 3.7 K. In the samples synthesized with Pt-rich nominal compositions (0.8 $\leq$ x $\leq$ 1.0), Sr$_{2}$(Pd,Pt)$_{8-y}$As$_{1+y}$ with an intergrowth structure (CS-orthorhombic with Cmcm) was crystallized. The phase diagram obtained for Sr(Pd,Pt)$_{3}$As was analogous to that of (Ca,Sr)Pd$_{3}$P in that superconductivity ($T_\mathrm{c}$ $\geq$ 2 K) occurred in the CS phases induced by substitutions to the NCS phases. This study indicates the potential for further material variation expansion and the importance of elemental substitutions to reveal hidden phases in related antiperovskites.