CAREER: Confining Magnetism to Two-Dimensions in Transition Metal Oxide Atomic Layers

North Carolina State University, Raleigh NC

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: As the dimensions of materials in modern devices approach thicknesses close to a few atomic layers, small deviations in atomic arrangements can occur leading to electronic and magnetic properties which differ vastly from the properties of the bulk materials. Using advanced synthesis tools which permit the combination of atomic layers of materials with different compositions, the atomic deviations can be effectively manipulated to produce novel effects. In this project, high-intensity X-rays are used to image the atomic-scale structure of the interfaces of layers of thin crystalline oxide films. The information gained from imaging these materials is required to help scientists and engineers understand why some oxide materials lose their useful magnetic properties when their thicknesses are reduced to a few atomic layers. The X-ray results are combined with high-resolution electron microscopy, magnetic and transport measurements, and theoretical calculations to design specific combinations of oxide materials to achieve magnetism in single layers of oxide materials. This project has exciting implications for the design of novel materials and devices for information processing, quantum computing and low-powered sensors. This project provides a highly collaborative environment and access to advanced technical resources for training undergraduate and graduate students in the development of the next generation of advanced nanoscale materials. The project provides low-cost tools for visualizing abstract concepts related to crystallography to foster the public understanding of the development of new technologically-relevant crystalline materials. TECHNICAL DETAILS: This project uses state-of-the-art synchrotron X-ray facilities at the Argonne National Laboratory and the Berkeley National Laboratory to carry out three-dimensional non-destructive atomic-scale mapping of the atomic, electronic and magnetic structures of magnetic perovskite oxide surfaces and interfaces. This research provides a comprehensive understanding of the fundamental interactions which occur at the interfaces between atomically-thin magnetic oxide films and other polar and non-polar perovskite materials and establishes a link between the observed interactions and the physical properties of these systems. A combination of first principles theory, high-resolution electron microscopy and temperature-dependent magnetic, transport and element-specific synchrotron X-ray magnetic dichroism measurements is used to design novel oxide heterointerfaces for achieving the confinement of ferromagnetism in two-dimensional oxide layers. These materials have applications in novel spin-based electronic devices. The wide range of cutting-edge research tools utilized in this activity are used to enhance the education of undergraduate and graduate students to prepare them for careers in scientific research and materials and device engineering. An important component of this project is the development of low-cost augmented reality tools for visualizing complex atomic and electronic structures for classroom instruction and public outreach to K-12 schools. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.