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Abstract Emerging non-volatile memristor-based devices with resistive switching (RS) materials are being widely researched as promising contenders for the next generation of data storage and neuromorphic technologies. Titanium nitride (TiN_x) is a common industry-friendly electrode system for RS; however, the precise TiN_xproperties required for optimum RS performance is still lacking. Herein, using ion-assisted DC magnetron sputtering, we demonstrate the key importance not only of engineering the TiN_xbottom electrodes to be dense, smooth, and conductive, but also understoichiometric in N. With these properties, RS in HfO₂-based memristive devices is shown to be optimised for TiN_0.96. These devices have switching voltages ≤ ±1 V with promising device-to-device uniformity, endurance, memory window of ~40, and multiple non-volatile intermediate conductance levels. This study highlights the importance of precise tuning of TiN_xbottom electrodes to achieve robust performance of oxide resistive switching materials. 

Tuning spin and charge degrees of freedom of complex oxide materials can enable significant advancements in future spintronics. In this study, by three dimensional strain engineering, we demonstrate room temperature ferroelectricity and magnetoelectricity in a vertically aligned nanocomposite thin film structure, composed of vertical nanopillars of SmFeO3 (SFO) embedded within the NiFeO4 (NFO) matrix. A three-dimensional tensile strain is induced in the SFO as a result of the unique film architecture. The tensile strain in SFO produces strong room temperature ferroelectric response instead of the normally very weak ferroelectricity of unstrained SFO, which is an improper ferroelectric. The induced ferroelectricity in SFO enables self-biased magnetoelectric coupling to be achieved between the two phases (magnetoelectric coupling coefficient ∼4 × 10−11 sm−1 at room temperature). The magnetoelectric coupling is facilitated by strain transfer across the vertical interfaces of the two phases. We additionally observe an exchange bias of ∼200 Oe (at 2 K) surviving up to the room temperature, indicating strongly coupled interfaces of SFO and NFO. These findings represent a step forward in future magnetoelectric RAM devices. 

An epitaxial NbN–Co VAN thin film was deposited on a MgO substrate with a cubic NbN phase, which presents ferromagnet properties with strong out-of-plane magnetic anisotropy. This hybrid metamaterial could find future applications in device design. 

Abstract Nanocomposite thin films, comprising two or more distinct materials at nanoscale, have attracted significant research interest considering their potential of integrating multiple functionalities for advanced applications in electronics, energy storage, photonics, photovoltaics, and sensing. Among various fabrication technologies, a one-step pulsed laser deposition process enables the self-assembly of materials into vertically aligned nanocomposites (VANs). The demonstrated VAN systems include oxide–oxide, oxide–metal, and nitride–metal VAN films and their growth mechanisms are vastly different. These complexities pose challenges in the designs, materials selection, and prediction of the resulted VAN morphologies and properties. The review examines the key roles that surface energy plays in the VAN growth and provides a generalized materials design guideline combining the two key factors of surface energy and lattice strain/mismatch, along with other factors related to growth kinetics that collectively influence the morphology of VAN films. This review aims to offer valuable guidelines for future material selection and microstructure design in the development of self-assembled VAN films. 

Resistive switching devices are promising candidates for the next generation of nonvolatile memory and neuromorphic computing applications. Despite the advantages in retention and on/off ratio, filamentary-based memristors still suffer from challenges, particularly endurance (flash being a benchmark system showing 10⁴to 10⁶ cycles) and uniformity. Here, we use WO₃as a complementary metal-oxide semiconductor–compatible switching oxide and demonstrate a proof-of-concept materials design approach to enhance endurance and device-to-device uniformity in WO₃-based memristive devices while preserving other performance metrics. These devices show stable resistive switching behavior with >10⁶ cycles, >10⁵-second retention, >10 on/off ratio, and good device-to-device uniformity, without using current compliance. All these metrics are achieved using a one-step pulsed laser deposition process to create self-assembled nanocomposite thin films that have regular guided filaments of ≈100-nanometer pitch, preformed between WO₃grains and interspersed smaller Ce₂O₃grains.