Emergence of a ZO Kohn anomaly in quasi-freestanding epitaxial graphene

Antonio Politano, Fernando de Juan, Gennaro Chiarello +1

In neutral graphene, two prominent cusps known as Kohn anomalies are found in the phonon dispersion of the highest optical phonon at $q=\Gamma$ (LO branch) and $q=K$ (TO branch), reflec…