文章基本信息

标题：Na1−xSn2P2 as a new member of van der Waals-type layered tin pnictide superconductors
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作者：Yosuke Goto ; Akira Miura ; Chikako Moriyoshi 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2018
卷号：8
期号：1
页码：12852
DOI：10.1038/s41598-018-31295-8
语种：English
出版社：Springer Nature
摘要：Superconductors with a van der Waals (vdW) structure have attracted a considerable interest because of the possibility for truly two-dimensional (2D) superconducting systems. We recently reported NaSn₂As₂ as a novel vdW-type superconductor with transition temperature ( T _c) of 1.3 K. Herein, we present the crystal structure and superconductivity of new material Na_{1− x}Sn₂P₂ with T _c = 2.0 K. Its crystal structure consists of two layers of a buckled honeycomb network of SnP, bound by the vdW forces and separated by Na ions, as similar to that of NaSn₂As₂. Amount of Na deficiency ( x ) was estimated to be 0.074(18) using synchrotron X-ray diffraction. Bulk nature of superconductivity was confirmed by the measurements of electrical resistivity, magnetic susceptibility, and specific heat. First-principles calculation using density functional theory shows that Na_{1− x}Sn₂P₂ and NaSn₂As₂ have comparable electronic structure, suggesting higher T _c of Na_{1− x}Sn₂P₂ resulted from increased density of states at the Fermi level due to Na deficiency. Because there are various structural analogues with tin-pnictide (SnPn) conducting layers, our results indicate that SnPn-based layered compounds can be categorized into a novel family of vdW-type superconductors, providing a new platform for studies on physics and chemistry of low-dimensional superconductors.