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

The gigantic magneto-optical effects in multilayers of two-dimensional (2D) semiconductor titania nanosheets, were analyzed. T_0.8Co _0.2O₂ was chosen to serve as a magnetic layer in multilayer assemblies because titania nanosheets can be heavily substituted by 3D magnetic elements. In these nanosheets, the film shows pronounced magnetic circular dichroism (MCD) structures around the absorption edge at 4.1 and 4.6 eV, which are closely correlated with critical points in absorption spectrum. The magneto-optical Kerr measurements exhibit that Co-substituted titania nanosheets act as nanoscale ferromagnetic layers at room temperature (RT), and their multilayer assemblies exhibit robust MCD near the absorption edge at 260 nm.