Prussian Blue Memristors Show Reliable Switching for Secure Data Storage

Prussian Blue thin films fabricated electrochemically exhibit reliable bipolar resistive switching behaviour over 100 cycles. Statistical analysis quantified moderate variability in switching parameters, confirming suitability for cryptographic applications such as physical unclonable functions and true random number generation, positioning the material as a viable memory candidate.

The pursuit of next-generation, non-volatile memory technologies increasingly focuses on materials exhibiting resistive switching (RS) – the ability to change electrical resistance under applied voltage. This behaviour offers potential for high-density data storage and neuromorphic computing. Researchers are now meticulously characterising the consistency of these devices, a critical step towards reliable implementation. A collaborative team, comprising L. B. Avila and F. Abreu Araujo from the Institute of Condensed Matter and Nanosciences (ICMN), Université catholique de Louvain, alongside A. Cantudo, M.A. Villena, D. Maldonado, J. B. Roldán from the Departamento de Electrónica y Tecnología de Computadores, Universidad de Granada, and C. K. Müller from the University of Applied Sciences Zwickau, detail their analysis in the article ‘Variability analysis in memristors based on electrodeposited prussian blue’. Their work investigates the cycle-to-cycle consistency of memristors fabricated from Prussian Blue – a coordination complex of iron – deposited as thin films, assessing their suitability for applications demanding predictable performance, such as hardware cryptography and random number generation.

Prussian Blue Memristors Exhibit Variability Suitable for Cryptographic Applications

This research presents a detailed characterisation of resistive switching (RS) behaviour in thin films of Prussian Blue – a mixed-valence iron compound – fabricated using a scalable electrochemical process. The investigation focused on assessing the suitability of these films as memristors – electronic devices whose resistance depends on the history of applied voltage or current – for both standard memory applications and, critically, hardware cryptography. A statistical analysis, encompassing 100 switching cycles, extracted key parameters including set and reset voltages and currents to quantify both device-to-device and cycle-to-cycle variability.

The central finding concerns the moderate level of variability observed in the resistive switching characteristics. This does not impede functionality, but instead presents compatibility with cryptographic applications, potentially enabling novel security solutions. Researchers employed both one-dimensional (1DCV) and two-dimensional (2DCV) coefficients of variation to rigorously quantify this variability, ensuring a comprehensive understanding of device behaviour. The coefficient of variation (CV) is a statistical measure of the dispersion of data around its mean.

Specifically, the observed characteristics position Prussian Blue memristors as potential building blocks for physical unclonable functions (PUFs) and true random number generators (TRNGs), both critical components in modern security systems. PUFs exploit inherent, random physical variations in a device to create a unique ‘fingerprint’, providing a robust authentication mechanism against counterfeiting and unauthorised access. TRNGs, conversely, rely on genuinely random physical processes to generate unpredictable numbers, essential for cryptographic applications such as encryption and secure communication.

The study highlights the robustness of the bipolar resistive switching exhibited by the Prussian Blue films, offering advantages over alternative switching mechanisms. Bipolar switching requires a specific voltage polarity to induce a change in resistance, offering improved stability and reduced power consumption compared to unipolar switching, which can exhibit unwanted state changes. This characteristic makes Prussian Blue memristors particularly attractive for energy-constrained applications, such as mobile devices and Internet of Things (IoT) sensors.

The electrochemical fabrication process’s simplicity and scalability further enhance the material’s attractiveness for large-scale integration, potentially enabling cost-effective manufacturing.

This research establishes Prussian Blue memristors as potential components for secure systems. The moderate variability observed is compatible with cryptographic applications, and the robustness of bipolar resistive switching makes these devices attractive for low-power applications.