SnAs-Based Layered Superconductor NaSn2As2

Superconducting behavior with exotic characteristics is often observed in materials with a layered two-dimensional crystal structure. Low dimensionality affects the electronic structure of these materials, potentially leading to high transition temperatures (T-c) and/or unconventional pairing mechanisms. In this letter, we report on superconductivity in layered tin arsenide NaSn2As2. The crystal structure consists of Sn2As2 bilayers, bound by the van der Waals forces and separated by Na+ ions. Measurements of electrical resistivity and specific heat confirm the bulk nature of superconductivity of NaSn2As2, with T-c of 1.3 K. Our results suggest that layered SnAs is a basic structure, offering another universality class in the family of layered superconductors. The results provide a new platform for the studies of physics and chemistry of low-dimensional superconductors with lone pair electrons.