  In the Kerr rotation geometry, magneto optic memory devices typically suffer
from low figure-of-merit (FOM) and long write times. We show that skyrmions
formed at the interface of a thin-film multiferroic and a topological insulator
can give rise to high FOM magneto optic Kerr effects (MOKEs). Huge differential
MOKE can arise in parts of the phase diagram. Resonance like features in the
MOKE spectra arising from the induced low energy TI bandgap, the
multiferroic-film thickness, and the high energy Drude like behavior are
resolved and explained. The Fermi level dependence of the MOKE signatures is
distinct for the different magnetic textures. This has broad implications for
magnetic texture characterization, electro-optic modulators and isolators and
high density magnetic optic memory.
