Enhanced superconductivity by Na doping in SnAs-based layered compound Na${}_{1+x}$Sn${}_{2-x}$As${}_2$

Abstract

Superconducting transition temperature (Tc) reported in SnAs-based layered compound NaSn${}_2$As${}_2$ varies from 1.2 to 1.6 K, implying that its superconductivity is critically sensitive to non-stoichiometry. Here, we demonstrate that Na-doping on the Sn site (Na${}_{1+x}$Sn${}_{2-x}$As${}_2$) is effective in enhancing superconductivity, leading to Tc = 2.1 K for x = 0.4. First-principles calculation indicates that such a doping, or Na${}_{\mathrm{Sn}}$ antisite defects, is energetically favored over other cation vacancies. Our results pave the way for increasing Tc of layered tin pnictide superconductors.

arXiv comment21 pages, 9 figures, 1 Table

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