脳を模倣したAI向けニューロモルフィックチップを開発（How can AI be more energy efficient? UB researchers look to human brain for inspiration）

2025-07-01 バッファロー大学（UB）

＜関連情報＞

• https://www.buffalo.edu/news/releases/2025/07/neuromorphic-computing.html
• https://www.arxiv.org/abs/2501.01822
• https://advanced.onlinelibrary.wiley.com/doi/10.1002/aelm.202400877
• https://pubs.acs.org/doi/10.1021/jacs.4c11968

熱的に安定なゼオライトイミダゾレート骨格（ZIF-8）抵抗スイッチングデバイスにおける再構成可能なフィラメント伝導 Reconfigurable Filamentary Conduction in Thermally Stable Zeolitic Imidazolate Framework (ZIF-8) Resistive Switching Devices

Divya Kaushik, Nitin Kumar, Harshit Sharma, Pukhraj Prajapat, Mehamalini V., G.Sambandamurthy, Ritu Srivastava
arXiv  Submitted on 3 Jan 2025
DOI:https://doi.org/10.48550/arXiv.2501.01822

Abstract

The rapid growth of digital technology has driven the need for efficient storage solutions, positioning memristors as promising candidates for next-generation non-volatile memory (NVM) due to their superior electrical properties. Organic and inorganic materials each offer distinct advantages for resistive switching (RS) performance, while hybrid materials like metal-organic frameworks (MOFs) combine the strengths of both. In this study, we present a resistive random-access memory (ReRAM) device utilizing zeolitic imidazolate framework (ZIF-8), a MOF material, as the resistive switching layer. The ZIF-8 film was synthesized via a simple solution process method at room temperature and subsequently characterized. The Al/ZIF-8/ITO device demonstrates bipolar resistive switching behaviour with an on/off resistance ratio of 100, stable retention up to 10000 seconds, and consistent performance across 60 cycles while exhibiting robust thermal stability from -20 C to 100 C. Low-frequency noise and impedance spectroscopy measurements suggest a filamentary switching mechanism. Additionally, the memory state can be tuned by adjusting the reset voltage, pointing to potential as multi-level memory. Potentiation and depression experiments further highlight the devices promise for neuromorphic applications. With high stability, tunability, and strong performance, the ZIF-8 based ReRAM shows great promise for advanced NVM and neuromorphic computing applications.

二重抵抗スイッチングNbO2メモリスタにおけるノイズ分光と電気伝導 Noise Spectroscopy and Electrical Transport In NbO2 Memristors with Dual Resistive Switching

Nitin Kumar, Jong E. Han, Karsten Beckmann, Nathaniel Cady, G. Sambandamurthy
Advanced Electronic Materials  Published: 13 February 2025
DOI:https://doi.org/10.1002/aelm.202400877

Abstract

Negative differential resistance (NDR) behavior observed in several transition metal oxides is crucial for developing next-generation memory devices and neuromorphic computing systems. NbO₂-based memristors exhibit two regions of NDR at room temperature, making them promising candidates for such applications. Despite this potential, the physical mechanisms behind the onset and the ability to engineer these NDR regions remain unclear, hindering further development of these devices for applications. This study employed electrical transport and ultra-low frequency noise spectroscopy measurements to investigate two distinct NDR phenomena in nanoscale thin films of NbO₂. By analyzing the residual current fluctuations as a function of time, spatially inhomogeneous and non-linear conduction are found near NDR-1 and a two-state switching near NDR-2, leading to an insulator-to-metal (IMT) transition. The power spectral density of the residual fluctuations exhibits significantly elevated noise magnitudes around both NDR regions, providing insights into physical mechanisms and device size scaling for electronic applications. A simple theoretical model, based on the dimerization of correlated insulators, offers a comprehensive explanation of observed transport and noise behaviors near NDRs, affirming the presence of non-linear conduction followed by an IMT connecting macroscopic device response to transport signatures at the atomic level.

ε-Cu 0.9 V 2 O 5ニューロモルフィック単結晶発振器におけるコンダクタンススイッチングの原子論的起源 Atomistic Origins of Conductance Switching in an ε-Cu0.9V2O5 Neuromorphic Single Crystal Oscillator

John Ponis,Nicholas Jerla,George Agbeworvi,Saul Perez-Beltran,Nitin Kumar,Kenna Ashen,Jialu Li,Edrick Wang,Michelle A. Smeaton,Fatme Jardali,Sarbajeet Chakraborty,Patrick J. Shamberger,Katherine L. Jungjohann,Conan Weiland,Cherno Jaye,Lu Ma,Daniel Fischer,Jinghua Guo,G. Sambandamurthy,Xiaofeng Qian,and Sarbajit Banerjee
Journal of the American Chemical Society  Published: December 4, 2024
DOI:https://doi.org/10.1021/jacs.4c11968

Abstract

Building artificial neurons and synapses is key to achieving the promise of energy efficiency and acceleration envisioned for brain-inspired information processing. Emulating the spiking behavior of biological neurons in physical materials requires precise programming of conductance nonlinearities. Strong correlated solid-state compounds exhibit pronounced nonlinearities such as metal–insulator transitions arising from dynamic electron–electron and electron–lattice interactions. However, a detailed understanding of atomic rearrangements and their implications for electronic structure remains obscure. In this work, we unveil discontinuous conductance switching from an antiferromagnetic insulator to a paramagnetic metal in ε-Cu_0.9V₂O₅. Distinctively, fashioning nonlinear dynamical oscillators from entire millimeter-sized crystals allows us to map the structural transformations underpinning conductance switching at an atomistic scale using single-crystal X-ray diffraction. We observe superlattice ordering of Cu ions between [V₄O₁₀] layers at low temperatures, a direct result of interchain Cu-ion migration and intrachain reorganization. The resulting charge and spin ordering along the vanadium oxide framework stabilizes an insulating state. Using X-ray absorption and emission spectroscopies, assigned with the aid of electronic structure calculations and measurements of partially and completely decuprated samples, we find that Cu 3d and V 3d orbitals are closely overlapped near the Fermi level. The filling and overlap of these states, specifically the narrowing/broadening of V 3d_xy states near the Fermi level, mediate conductance switching upon Cu-ion rearrangement. Understanding the mechanisms of conductance nonlinearities in terms of ion motion along specific trajectories can enable the atomistic design of neuromorphic active elements through strategies such as cointercalation and site-selective modification.