Superconductivity of Bulk Abnormal Magic-stoichiometric Na3Cl Salt Crystals at Normal Pressure

TL;DR

This study predicts that Na3Cl, a simple salt, can become a superconductor at normal pressure due to its unique stoichiometry and electronic structure, with potential implications for designing new superconducting materials.

Contribution

First-principles calculations reveal Na3Cl with abnormal 3:1 stoichiometry as a new bulk superconductor at normal pressure, highlighting a novel approach to discovering superconductors.

Findings

Na3Cl exhibits superconductivity with Tc of 0.13 K.

The crystal features flat bands and van Hove singularities near the Fermi level.

The methodology may be applicable to other elements for superconductor design.

Abstract

The identification of new materials with superconducting properties is the pursuit in the realm of superconductivity research. Here, excitedly, we show that the simplest salt daily used can be made a superconductor at normal pressure only by adjusting its stoichiometry of Na and Cl as Na3Cl at normal pressure based on first-principles calculations. This bulk stable abnormal Na-Cl stoichiometric crystal of 3:1, the first 'magic' ratio, includes metallic (Na) atoms in the core as well as hybridization of ionic and metallic bonding, facilitating the electron-phonon-coupling for superconductivity with a critical temperature Tc of 0.13 K. The flat bands and van Hove singularities near the Fermi level produce large densities of states, similar to H3S and LaH10, which is beneficial for the emergence of superconductivity. The crystal composed of with abnormal Na-Cl magic stoichiometry is a precisely tunable, purely sodium and chloride-based, three-dimensional bulk superconductor, which is therefore an ideal material for designing and understanding abnormal stoichiometric crystals. The methodology of constructing this bulk abnormal crystal may be general to almost all elements, which could lead to insights into the physics of other conventional superconductors and even high-critical-temperature superconductors.