Three-dimensional strain engineering in epitaxial vertically aligned nanocomposite thin films with tunable magnetotransport properties

Abstract

Three-dimensional (3D) frameworks have been successfully constructed by interlayering La_0.7Sr_0.3MnO₃ (LSMO)–CeO₂ based epitaxial vertically aligned nanocomposite (VAN) thin films with pure CeO₂ (or LSMO) layers. Such 3D interconnected CeO₂ scaffolds integrate the lateral film strain by the interlayers with the vertical strain in VAN layers, and thus achieve the maximized strain tuning in LSMO. More importantly, by varying the types of the interlayers (i.e., CeO₂ or LSMO) and the number of interlayers from 1 to 3 layers, such 3D framework nanostructures effectively tune the electrical transport properties of LSMO, e.g., from a 3D insulating CeO₂ framework with integrated magnetic tunnel junction structures, to a 3D conducting LSMO framework, where the magnetoresistance (MR) peak values have been tuned systematically to a record high of 66% at 56 K and enhanced MR properties at high temperatures above room temperature (∼325 K). This new 3D framed design provides a novel approach in maximizing film strain, enhancing strain-driven functionalities, and manipulating the electrical transport properties effectively.