Superconductivity in Li3Ca2C6 intercalated graphite

TL;DR

This paper reports the discovery of superconductivity in the Li3Ca2C6 graphite intercalation compound, with a critical temperature close to that of CaC6, highlighting the role of intercalation in inducing superconductivity in graphite.

Contribution

It presents the first observation of superconductivity in Li3Ca2C6, a ternary GIC with thick intercalated layers, expanding the understanding of superconductivity in graphite intercalation compounds.

Findings

Superconductivity observed at 11.15 K in Li3Ca2C6

Li3Ca2C6 has a critical temperature close to CaC6

Intercalation induces superconductivity in graphite-based materials

Abstract

In this letter, we report the discovery of superconductivity in Li3Ca2C6. Several graphite intercalation compounds (GICs) with electron donors, are well known as superconductors. It is probably not astonishing, since it is generally admitted that low dimensionality promotes high superconducting transition temperatures. Superconductivity is lacking in pristine graphite, but after charging the graphene planes by intercalation, its electronic properties change considerably and superconducting behaviour can appear. Li3Ca2C6 is a ternary GIC, for which the intercalated sheets are very thick and poly-layered (five lithium layers and two calcium ones). It contains a great amount of metal (five metallic atoms for six carbon ones). Its critical temperature of 11.15 K is very close to that of CaC6 GIC (11.5 K). Both CaC6 and Li3Ca2C6 GICs possess currently the highest transition temperatures among all the GICs.