Significant effects of epitaxial strain on the nonlinear transport properties in Ca2RuO4 thin films with the current-driven transition

Abstract

Control of the nonlinear transport properties in strongly correlated materials with metal–insulator transitions has become an important task in the development of next-generation computing elements. Here, we demonstrate that the nonlinear transport properties in the Mott insulator Ca2RuO4, which are caused by the current-driven transition with a nonthermal-type mechanism, can be significantly affected by epitaxial strain in thin films. Ca2RuO4 epitaxial thin films were grown on various single-crystal substrates by the solid-phase epitaxy method under nonvacuum conditions, and the effects of epitaxial strain on the transport properties were investigated. While nonlinear transport properties with negative differential resistance behavior were observed in [001]-oriented Ca2RuO4/LaAlO3 (001) thin films, the current transport nonlinearity was critically diminished in the current–voltage characteristics of Ca2RuO4/NdCaAlO4 (100) thin films with the [110] orientation. Through structural characterization of the thin films, a possible correlation between the strain states and nonlinear transport properties was discussed.