Impact of metal silicide nanocrystals on the resistance ratio in resistive switching of epitaxial Fe₃O₄ films on Si substrates

Fe₃O₄ films on Si substrates have been intensively studied for the realization of resistance random access memory composed of only ubiquitous elements. The biggest issue for the application of Fe₃O₄ film/Si in small-scaled devices is the low Off/On resistance ratio. For the enhancement of the Off/On resistance ratio, we propose epitaxial Fe₃O₄ films including hemispherical small metal α-FeSi₂ nanocrystals on Si substrates, where an electric field is concentrated at the interface between Fe₃O₄/α-FeSi₂. The concentrated electric field largely promotes the movement of oxygen ions, contributing to resistive switching. As a result, the Fe₃O₄ films including hemispherical small α-FeSi₂ nanocrystals exhibit the largest Off/On resistance ratio (∼200) in Fe₃O₄-based nanomaterials. Finite element method simulations proved that the introduction of metal nanocrystals into films caused the enhancement of electric field intensity near the interface between nanocrystals and films. This significant enhancement method will open an avenue for realizing high-performance ubiquitous-element resistive switching materials in the next-generation information society.