Multifilamentary character of anticorrelated capacitive and resistive switching in memristive structures based on (CoFeB)x(LiNbO3)100-x nanocomposite

TL;DR

This study investigates the resistive and capacitive switching behaviors in nanocomposite-based memristive structures, revealing a multifilamentary switching mechanism and significant capacity changes linked to structural features.

Contribution

It introduces a novel model explaining the multifilamentary resistive and capacitive switching in (CoFeB)x(LiNbO3)100-x nanocomposite structures, supported by experimental and magnetic studies.

Findings

Capacitance increases up to 8 times during switching.

Resistance ratio Roff/Ron reaches approximately 40.

Structural features like LiNbO3 layers influence switching behavior.

Abstract

Resistive and capacitive switching in capacitor metal/nanocomposite/metal (M/NC/M) structures based on (CoFeB)x(LiNbO3)100-x NC fabricated by ion-beam sputtering with metal content x $\approx$ 8-20 at. % is studied. The peculiarity of the structure synthesis was the use of increased oxygen content ($\approx$ 2*10^-5 Torr) at the initial stage of the NC growth. The NC films, along with metal nanogranules of 3-6 nm in size, contained a large number of dispersed Co (Fe) atoms (up to ~10^22 cm^-3). Measurements were performed both in DC and AC (frequency range 5-13 MHz) regimes. When switching structures from high-resistance (Roff) to low-resistance (Ron) state, the effect of a strong increase in their capacity was found, which reaches 8 times at x $\approx$ 15 at. % and the resistance ratio Roff/Ron $\approx$ 40. The effect is explained by the synergetic combination of the multifilamentary character of resistive switching (RS) and structural features of the samples associated, in particular, with the formation of high-resistance and strongly polarizable LiNbO3 layer near the bottom electrode of the structures. The proposed model is confirmed by investigations of RS of two-layer nanoscale M/NC/LiNbO3/M structures as well as by studies of the magnetization of M/NC/M structures in the pristine state and after RS.