GOALI: Local Measurement of Superconducting Nonlinearities

University Of Maryland, College Park, College Park MD

Investigators

Abstract

The identification and elimination of defects that produce nonlinearity in superconducting microwave materials and devices is an important goal for the superconducting microwave industry. The measurement of the nonlinear Meissner effect in d-wave superconductors is a key goal of fundamental condensed matter research. This GOALI award supports a project uniting the efforts of an investigator at an academic research laboratory with two corporate research entities, ISCO International and Neocera, in order to locally measure nonlinearities in superconductors. The experimental methods employed for the fundamental research will help the practical project, and vice versa. The expected outcomes of this project are: 1) the most sensitive measurement of the intrinsic nonlinear Meissner effect in d-wave and s-wave superconductors, and 2) identification and elimination of specific extrinsic defects that cause microwave nonlinearities in practical superconducting materials. The research contributions of the industrial partners include: assistance with the scanning near-field microwave measurements, providing materials for imaging, helping to understand the complicated microstructure of oxide superconductors, helping to identify and eliminate extrinsic sources of nonlinearity from the materials, and helping to bring the practical aspects of our research to the applied community. Through this project it is expected that new local electrodynamics measurements in superconductors will be made possible. This work will provide key tests of theories of cuprate superconductivity, and open up new applications of high-Tc superconducting materials in wireless and high-speed device applications. Two graduate students will be trained in skills necessary for high-tech careers and will benefit from the close collaboration with industry. There will also be substantial outreach activities to engage elementary and secondary schools students. High Temperature Superconductors (HTS) have begun to make an impact on the commercial wireless communications field. Because of their low resistance and compact size, HTS thin films produce superior performance when used to filter out un-wanted signals in wireless telephone base stations. This translates into improved call quality, longer range and fewer dropped calls for the wireless consumer, and greater profits for the wireless operators. However, these advantages are jeopardized by uncontrolled defects and disorder in the superconducting materials used to make these devices. These defects limit the use of HTS materials to low power receive applications, and prevent the benefits of superconductivity from being achieved in high power transmit applications. This GOALI award supports a microscopic investigation of the sources of these defects and disorder. The project is also an effort to work with manufacturers of HTS thin films and wireless devices to eliminate these defects and therefore substantially enhance their products. In addition the project involves synergistic fundamental research that will focus on basic measurements of superconducting nonlinear properties and use these measurements to rigorously test the leading theories of high temperature superconductivity. Two graduate students will be trained in skills necessary for high-tech careers and will benefit from the close collaboration with industry. There will also be substantial outreach activities to engage elementary and secondary schools students.