Controllable Self-Assembled Microstructures of La0.7Ca0.3MnO3:NiO Nanocomposite Thin Films and Their Tunable Functional Properties

Two-phase self-assembled nanocomposite films have attracted increasing interest in recent years because of their potential applications in novel technological devices. However, tuning the physical properties by modulating the microstructure of self-assembled nanocomposite films is still a challenge. In this study, epitaxial La0.7Ca0.3MnO3:NiO nanocomposite films are synthesized by pulsed laser deposition. In the composite films with a NiO ratio of 50%, microstructures with nanomultilayer, nanogranular, and nanocolumnar characteristics are successfully obtained by using different growth modes. The metal-insulator transition and magnetic transition can be separately modulated by tuning the microstructures. By precisely modulating the microstructure, a significantly enhanced low-field magnetoresistance (>80% at a magnetic field of 1 T) with an unusual plateau in the temperature interval from 10 to 110 K is realized in these films, which is expected to be applicable in field-sensor devices that can be operated in a wide temperature range.