Pressure-Induced Superconductivity and Structure Phase Transition in SnAs-Based Zintl Compound SrSn2As2

Abstract

Layered SnAs-based Zintl compounds exhibit a distinctive electronic structure, igniting extensive research efforts in areas of superconductivity, topological insulators, and quantum magnetism. In this paper, the crystal structures and electronic properties of the Zintl compound SrSn₂As₂ upon compression are systematically investigated. Pressure-induced superconductivity is observed in SrSn₂As₂ with a nonmonotonic evolution of superconducting transition temperature T_c. Theoretical calculations together with high-pressure synchrotron X-ray diffraction and Raman spectroscopy have identified that SrSn₂As₂ undergoes a structural transformation from a rhombohedral R$$m phase to the monoclinic C2/m phase. Beyond 28.3 GPa, T_c is suppressed due to a reduction of the density of state (DOS) at the Fermi level. The discovery of pressure-induced superconductivity, accompanied by structural transitions in SrSn₂As₂, greatly expands the physical properties of layered SnAs-based compounds and provides new ground states upon compression.