The 4th International Conference on Matter and Radiation at Extremes (ICMRE 2019)

428 / 2019-03-01 14:16:10

Superconductivity in Li6P electride

Superconductivity; Structural prediction; First principles; High pressure

Plenary track > High Pressure Physics and Materials Science

Electrides are unique compounds where most of the electrons reside at interstitial regions of the crystal behaving as anions, which strongly determines its physical properties. Interestingly, the magnitude and distribution of interstitial electrons can be effectively modified either by modulating its chemical composition or external conditions (e.g. pressure). Most of the electrides under high pressure are non-metallic, and superconducting electrides are very rare. Here, we report that a pressure-induced stable Li6P electride, identified by first-principles swarm structure calculations, becomes a superconductor with a predicted superconducting transition temperature Tc of 39.3 K, which is the highest among already known electrides. The interstitial electrons in Li6P, with dumbbell-like connected electride states, play a dominant role in the superconducting transition. Other Li-rich phosphides, Li5P and Li8P, are also predicted to be superconducting electrides, but with a lower Tc. Superconductivity in all these compounds can be attributed to a combination of a weak electronegativity of P with a strong electropositivity of Li, and opens up the interest to explore high-temperature superconductivity in similar binary compounds.