Huge Differential Magneto Optic Kerr Effects of Interfacial Skyrmions on Topological Insulators*

Magneto optic memory devices typically suffer from low Kerr rotation angles and long write times. We show
that skyrmions formed at the interface of a thin-film multiferroic and a topological insulator (TI) can
give rise to huge magneto optic Kerr effects (MOKEs). The interfacial skyrmions are stabilized by the TI which can
also provide an additional electronic handle to switch between ferromagnetic and skyrmionic spin textures.
We show that this gives rise to an additional huge differential MOKE, and we carefully explore
its phase diagram. This system can lead to applications such as a topologically protected high density magnetic optic memory device with ultra-low error rates.