Lay summary
We propose a project aimed at developing new solid state devices by combining state-of-the-art nanofabrication with the exciting materials of contemporary condensed matter physics. Strongly correlated electron effects provide several classes of emerging transition-metal oxides with remarkable transport properties, including high-Tc superconductivity in layered cuprates and colossal magneto-resistance (CMR) in the cubic, layered and bi-layered manganites. In particular, the layered materials offer themselves as promising candidates for micro-fabrication of mesoscopic devices testing and exploiting their unique and tunable transport properties. We aim to fabricate and investigate devices based on the bilayer manganite La1.4Sr1.6Mn2O7, which orders magnetically below 90K, at which point both in-plane and c-axis resistivity de-crease by 2-3 orders of magnitude. Our mesoscopic devices will have dimensions comparable to a typical domain, allowing us to study structures going from a single domain to several domains. The first goal is to prove the proposed transport mechanism. Subsequently, our ambition is to control the domain wall structure in order to create spintronic devices. A single domain should exhibit enormous magnetoresistance (higher than giant magnetoresistance currently holding the record) at the magnetic field where adjacent layers switch from antiferromagnetic to ferromagnetic alignment. Exploiting the intrinsic spin-valve nature of this layered material for spintronic gates may bring significant advances in sizing and performance compared to artificially constructed multilayer structures and could lead to development of novel types of nonvolatile computer memory such as racetrack memory. While the current proposal concern a specifically selected material with a detailed research plan, it should be viewed as the starting point for wider activities with the general idea of coupling traditional solid state physics with nanofabrication technologies. Nanofabrication enables new fundamental studies of these materials and on the other hand also serves as a test-bed for practical applications of mesoscopic devices based on highly correlated electron systems.