Gigantic magneto-optical effects in multilayer assemblies of two-dimensional titania nanosheets

A two-dimensional titania nanosheet is proven to be useful as a host for spin-electronic materials. Magneto-optical measurements demonstrate that Co-substituted titania nanosheets (Ti-0.8-Co0.2O2) act as nanoscale ferromagnetic layers at room temperature, and their multilayer assemblies exhibit robust magnetic circular dichroism (MCD) in the ultraviolet-visible region. The availability of ferromagnetic nanostructures allows the rational design of high-efficiency magneto-optical devices.