To demonstrate the multifunctionality of the nanopatterned titanium oxide, we present the results of our investigation of various TiO₂-based systems. In the first case, we study the photoactivity of the highly ordered nanotubes, where we force the nanotube growth by manipulating the electric field distribution by introducing a layer of thin titanium antidots on the substrate surface. The addition of titanium antidots results in overcoming the physical limit of nanotube ordering from grain boundaries (a few um²) to several cm². By controlling the ordering, the photocatalytic reaction rate may be tuned in the range of 0.2 to 0.6 μmol L^-1min^-1 depending on the antidots' diameters.

The TiO₂ nanotubes create an array of artificially made surface defects with controllable parameters, enabling us to alter the magnetic properties of thin iron films, such as saturation magnetization and effective anisotropy constant. Moreover, the iron films partially oxidize at the titanium oxide/iron interface, inducing a two-phase magnetic composition with weak exchange interaction. Due to the formation of the nanocrystallites of iron oxide at the interface, the system shows an additional low-temperature glass-like magnetic state.

The nanopatterned titanium oxide may be used as an interlayer in heterojunctions, allowing manipulation of not only magnetic but also electric transport properties and magnetoresistance of the system. This method allowed us to fabricate the double-barrier Schottky junction with the following structure of trilayer: Ti/TiO_x/Fe. Such a junction exhibits magnetoresistance with different signs: positive at room temperature and negative at 5 K. The switching temperature decreases with an increase in the size of the nanotubes. Detailed characterization uncovers that the positive MR originates from the titanium/titanium oxide interface, and the negative MR arises from the titanium oxide/iron interface.