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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. 

Abstract Over the past decade, lead halide perovskites have gained significant interest for ionizing radiation detection, owing to their exceptional performance, and cost-effective fabrication in a wide range of form factors, from thick films to large single crystals. However, the toxicity of lead, limited environmental and thermal stability of these materials, as well as dark current drift due to ionic conductivity, have prompted the development of alternative materials that can address these challenges. Bismuth-based compounds (including perovskite derivatives and nonperovskite materials) have similarly high atomic numbers, leading to strong X-ray attenuation, but have lower toxicity, tend to be more environmentally stable, and can have lower ionic conductivity, especially in low-dimensional materials. These materials are also advantageous over commercial direct X-ray detectors by being able to detect lower dose rates of X-rays than amorphous selenium by at least two orders of magnitude, are potentially more cost-effective to mass produce than cadmium zinc telluride, and can operate at room temperature (unlike high-purity Ge). Given the strong interest in this area, we here discuss recent advances in the development of bismuth-based perovskite derivatives (with 3D, 2D and 0D structural dimensionality), and other bismuth-based perovskite-inspired materials for direct X-ray detection. We discuss the critical properties of these materials that underpin the strong performances achieved, particularly the ability to detect low-dose rates of X-rays. We cover key strategies for enhancing the performance of these materials, as well as the challenges that need to be overcome to commercialize these emerging technologies. Graphical abstract 

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. 

Highly promising performance for future computing applications is achieved based on a new materials design.