Vertex dominated superconductivity in intercalated FeSe

Swagata Acharya, Mikhail I. Katsnelson, Mark van Schilfgaarde

Bulk FeSe becomes superconducting below 9\,K, but the critical temperature (T${}_c$) is enhanced almost universally by a factor of $\sim$4-5 when it is intercalated with alkali ele…