Tailoring resistive switching in epitaxial SrCoO2.5 films by irradiation induced uniaxial strain

Strain engineering has been widely applied to tune the performance of oxide thin film based devices. To precisely regulate the strain state of the thin film, nevertheless, still remains a challenging task. Herein, we demonstrate that the uniaxial strain along the c-axis of epitaxial SrCoO2.5 (SCO) (001) thin film can be continuously controlled by low-energy helium (He) irradiation (5 keV), leading to noticeable enhancement in resistive switching (RS) performance. All the irradiated SCO thin films exhibit out-of-plane tensile strain due to the implanted He interstitials in the lattice, and the strain increases linearly from 0.447% to 2.785% as the ion fluence increases from 1 × 1014 to 1 × 1015 ion/cm2. Although all the irradiated SCO-based devices follow similar conductive filaments mechanism as the pristine device, the performance shows a volcano shape dependence on the irradiation fluence. The device subjected to irradiation of 1 × 1014 ion/cm2 shows the optimal performance with the highest ON/OFF ratio and good endurance. Such dependence of RS behavior on irradiation-induced uniaxial strain is attributed to the widely observed nonlinear dependence of oxygen migration on the elastic tensile strain. Our results provide an effective strategy to regulate the strain states and the correlating functionality of oxide thin films.