Superconductivity in layered Zintl phase LiSn2As2

Abstract

We report the superconductivity in the layered Zintl phase LiSn2As2, which is isostructural to NaSn2As2 and has a transition temperature (Tc) of 1.6 K. Despite similar Tc and Debye temperatures, substituting of Na with Li considerably increases the upper critical field. Based on a systematically comparation of Sn4As3, NaSnAs, NaSn2As2,Na1−xSn2P2, SrSn2As2, and LiSn2As2, we propose that carrier doping, intimately related to the formation of lone-pair electrons, controls superconductivity in layered SnAs-based compounds rather than chemical pressure. The current findings provide a thorough and comprehensive understanding of Sn-based Zintl phase.