Harnessing diluted magnetic TiO2 for memristor-based information storage: Voltage-driven write/erase circuit

In this work, TiO2:Co nanotubes were fabricated via electrochemical anodization, using Ti foils (99.99% purity) as the cathode, onto which Co layers were deposited via DC magnetron sputtering. To design a nanotube-based memristor structure, PET tape composed of polyester with 0.05 mm thick, was used. With this PET tape, the active area was reduced to two square regions of 0.7 cm per side, separated by 0.3 cm. I-V measurements revealed a hysteresis-like behavior, with SET and RESET processes characteristic of resistive switching. Additionally, robustness tests at room temperature over 1200 cycles showed a slight increase in both, high and low resistance states (HRS and LRS, respectively) as the number of cycles was increased. This effect could be related to the stability of the conductive filament formation, influenced by the presence of Co in the material matrix, which may introduce defects that enhance the operating voltage and resistive switching behavior. The analysis of the current signal under the defined operating conditions of the memory unit confirmed that the resistive switching behavior of the device enables binary logic functionality, allowing it to operate as the core element of a logic system. The proposed device integrates four digital systems that interpret a discrete signal. Using demultiplexers and analog switches, it executes a write/read process by applying two electrical potentials (6 V and 2 V) to induce resistive changes in the material within a range of 2 MΩ to 100 Ω. These variations were subsequently interpreted as a binary structure through a comparator amplifier, which defines two digital states readable as a discrete signal.