Voltage-Driven Room-Temperature Resistance and Magnetization Switching in Ceramic TiO₂/PAA Nanoporous Composite Films

Abstract

Voltage control of room-temperature ferromagnetism has remained a big challenge which will greatly influence the multifunctional memory devices. In this paper, porous TiO2 thin films were deposited by dc-reactive magnetron sputtering onto ordered porous anodic alumina (PAA) substrates. Voltage-driving room-temperature resistance and magnetization switching without external magnetic field are simultaneously found in an Ag/TiO2/PAA/Al (Ag/TP/Al) device. Further analysis indicates that the formation/rupture of oxygen vacancy defect-based conductive filaments would be responsible for the changes of resistivity and magnetization. Our present results suggest that the TP nanoporous composite film material may therefore be used to achieve voltage control of magnetism and resistance switching in the future multifunctional memory devices. The Ag/TP/Al devices can also be used for new spintronic devices, neuromorphic operations, and alternative logic circuits and computing.

Mixed-Phase TiO2 Nanotube–Nanorod Hybrid Arrays for Memory-Based Resistive Switching Devices

“…51 The substantial amount of of oxygen vacancies in MX-TNHs may naturally form filaments on the inner walls of the TiO 2 nanotubes. 52 It was expected that the inner walls of the TiO 2 nanotubes would facilitate the incorporation of multiple filaments (more grain boundaries than a uniform film between an interface of an Al electrode and MxPh-TNs) or path generation of O 2− migration through the generation of a charge surface area with a higher possibility of conductive channels. 53 Additionally, when Al was used as the top electrode, electrochemical reactions at the interface were observed.…”

“…Oxygen vacancies work as electron traps in the SCLC system, which can diffuse via the substrate, induce more oxygen vacancies to be generated by an external applied voltage, and support the switching phenomenon . The substantial amount of of oxygen vacancies in MX-TNHs may naturally form filaments on the inner walls of the TiO 2 nanotubes . It was expected that the inner walls of the TiO 2 nanotubes would facilitate the incorporation of multiple filaments (more grain boundaries than a uniform film between an interface of an Al electrode and MxPh-TNs) or path generation of O 2– migration through the generation of a charge surface area with a higher possibility of conductive channels …”

Bipolar Electrochemical Anodization Route for the Fabrication of Porous Anodic Alumina with Nanopore Gradients

“…In recent years, electrochemical anodization technology has received increasing attention. − A porous anodic alumina (PAA) film prepared by anodization is a self-assembled hexagonal densely arranged nanoporous array structure. , Arrays of nanotubes, nanowires, and quantum dots composed of metals, alloys, nonmetals, polymers, and other materials have been successfully synthesized and assembled using PAA as a template in combination with electrochemical deposition, chemical or electrochemical polymerization, chemical vapor deposition, sol–gel methods, and electrophoretic deposition. − At present, this kind of PAA template has played an indispensable role in the field of fabrication of nanostructured materials and the PAA template method has become one of the most commonly used techniques for making nanostructures.…”

Growth Model of the Tin Anodizing Process and the Capacitive Performance of Porous Tin Oxides

“…The simple electrochemical method is also very convenient for wide applications. 5−12 It is universally acknowledged that simple anodization can enable fabrication of nanostructured oxide layers on the surface of various metals and alloys, such as Al, 6,7 Ti, 8,9 Pb, Co, Zr, 10,11 Ti-2Al-1.5Mn alloy, 12 etc. However, the formation mechanisms of these porous oxides are still controversial.…”

“…Contemporarily, nanostructured SnO 2 materials have potential application value in the fields of dye-sensitized solar cells, gas sensing, lithium-ion batteries, photoelectric catalysis, etc. The simple electrochemical method is also very convenient for wide applications. − It is universally acknowledged that simple anodization can enable fabrication of nanostructured oxide layers on the surface of various metals and alloys, such as Al, , Ti, , Pb, Co, Zr, , Ti-2Al-1.5Mn alloy, etc. However, the formation mechanisms of these porous oxides are still controversial. − In the same way, a simple one-step anodization carried out in oxalic acid − and alkaline (e.g., NaOH or NH 3 ) or sulfide- and fluoride-based electrolytes can also result in the formation of nanostructured SnO 2 . − In an alkaline electrolyte, a crack-free tin oxide layer can be fabricated via simple one-step anodization in NaOH at low applied potentials .…”