Magnetic behavior and conductive wall switching in TiO2 and TiO2:Co self-organized nanotube arrays

This work presents a study of the physical properties of self-organized nanotubes of TiO2 and Co doped TiO2, fabricated by an electrochemical anodized. The Co was deposited on titanium foils and TiO2 nanotubes, via DC magnetron co-sputtering, before and after anodization process. Here is proposed the formation of [TiF6](2-) and [CoF6](3-) complexes into solution during anodization process. It was possible to identify the presence of Anatase and Rutile phases in the nanotubes from XRD, Raman, and IR measurements. When the Co was deposited after anodized process on TiO2 nanotubes, Co3O4 phase was observed. Co concentration in TiO2:Co nanotubes was obtained through EDXS measurements. The morphological properties were modified due to applied the square voltage, evidenced by the bamboo nodes type in the topographical wall of nanotubes, through the HR-SEM micrographics. Curves I-V presents a SET and RESET processes and a switching of the nanotubes properties. This behavior was modified by an application of magnetic field. A conductivity switching mechanism model is proposed. Hysteresis loops were observed in the TiO2:Co self-organized nanotube arrays associated with the Co random distribution. (C) 2020 Elsevier B.V. All rights reserved.