Atomistic Origins of Conductance Switching in an ε-Cu0.9V2O5 Neuromorphic Single Crystal Oscillator

Published

December 4, 2024

Author(s)

Cherno Jaye, Conan Weiland, Daniel Fischer, 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, Lu Ma, Jinghua Guo, G Sambandamurthy, Xiaofeng Qian, Sarbajit Banerjee

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 non-linearities. Strong correlated solid-state compounds exhibit pronounced nonlinear-ities such as metal—insulator transitions arising from dynamic electron-electron and electron-lattice interactions. However, 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-Cu0.9V2O5. 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 inter-chain Cu-ion migration and intra-chain reorganization. The resulting charge and spin ordering along the vanadium oxide framework stabi-lizes an insulating state. Using X-ray absorption and emission spectroscopies, assigned with the aid of electronic structure calculations and measurements of partially and completely de-cuprated 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 narrowing/broadening of V 3dxy states near the Fermi level, mediates conductance switching upon Cu-ion rearrangement. Understanding mechanisms of conductance nonlinearities in terms of ion motion along specific trajectories can enable the atomistic design of neuromor-phic active elements through strategies such as through co-intercalation and site-selective modification.

Citation

ACS

Pub Type

Journals

Keywords

Metal-insulator transitions, Memrestive, Neuromorphic computing, XRD, HAXPES, XANES, EXAFS, RIXS, EDX, TEM

Citation

Jaye, C. , Weiland, C. , Fischer, D. , Ponis, J. , Jerla, N. , Agbeworvi, G. , Perez-Beltran, S. , Kumar, N. , Ashen, K. , Li, J. , Wang, E. , Smeaton, M. , Jardali, F. , Chakraborty, S. , Shamberger, P. , Jungjohann, K. , Ma, L. , Guo, J. , Sambandamurthy, G. , Qian, X. and Banerjee, S. (2024), Atomistic Origins of Conductance Switching in an ε-Cu0.9V2O5 Neuromorphic Single Crystal Oscillator, ACS (Accessed January 17, 2025)