  We demonstrate that memristive devices can be fabricated by tip-induced
oxidation of thin metallic films using atomic force microscope. Electrical
measurements of such prepared Ti/TiOx/Ti test structures confirmed their
memristive behavior and inferred diffusion of oxygen vacancies in the TiOx
barrier. Consequent Kelvin probe force microscopy studies provided evidence for
the diffusion, as well as for expected oxygen vacancy drift. Time evolution of
the space distribution of the vacancies due to the diffusion process revealed
minute-scale (at least) retention times of the devices. The work presents
technology alternative for fabrication of memristive nanodevices in geometry
favouring advantageous scanning probe microscopy studies of their in-barrier
processes, as well as widely utilizable approach to search for novel oxide
materials for perspective memristive applications.
