Ambient pressure superconductivity mediated by vanadium d electrons in electride 2H−VN2

Abstract

Electrides usually have topological properties and high electrical conductivity, so searching for superconducting electrides over a wide range of temperature and pressure is a hot topic in condensed matter physics. Based on high-throughput structure search and the first-principles calculations, we predict that 2H−VN2 is a thermodynamically and dynamically stable electride with the superconducting transition temperature (Tc) of 51 K at ambient pressure. From the calculations of the electronic localization function, it is found that the excess unpaired electrons of the V atoms are likely to exist in the lattice vacancies as interstitial electrons, which makes 2H−VN2 an electride. On the other hand, the existence of irreducible representation at the vacancies also confirms that 2H−VN2 is an electride. Moreover, the flat bands, primarily originating from the V-d orbitals, and the nesting of the Fermi surface induce a high density of states. This enhances the electron-phonon coupling (EPC) strength between the V-d orbitals and the phonon modes associated with the vibrations of N atoms. The calculated EPC strength of 2H−VN2 electride at ambient pressure is 1.06, and the superconducting gap vanishes at 51 K. We find that 2H−VN2 electride has a Tc of 51 K at ambient pressure, which gives a practicable method to connect the superconducting properties and the specificities of electrides in unitary material.

Source-reported materials — not catalogue approval

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