A Strategy for Fabricating Room-Temperature Cuprate Superconductors
Abstract
The ancient phrase, ???All roads lead to Rome??? applies to Chemistry and Physics. Both are highlyevolved sciences, with their own history, traditions, language, and approaches to problems.Despite all these differences, these two roads generally lead to the same place. For hightemperature cuprate superconductors however, the Chemistry and Physics roads do not meet oreven come close to each other. The Chemistry approach finds that hole doping in cuprates leadsto a localized out-of-the-CuO2-plane hole surrounding the dopant atom. The Physics approachfinds that the dopant creates a hole residing inside the CuO2 planes. The Physics hole state hasbeen investigated, mostly via Hubbard Models, for 31 years, yet it has not led to anunderstanding of the mechanism of superconductivity. Most significantly, the Physicist???stheories have provided no guidance to materials synthesis labs for fabricating higher temperatureand higher critical current superconductors.We have discovered that the Chemist???s picture leads to explanations of a vast array of normalstate cuprate phenomenology using simple counting arguments (seehttps://arxiv.org/abs/1702.05001). The chemistry picture suggests that phonons are responsiblefor superconductivity in cuprates and that there are dynamic Jahn-Teller distortions in thecuprates that lead to the observed D-Wave superconducting gap symmetry. Surprisingly, thetheory shows that room-temperature temperature superconductivity is possible in YBCO if thedynamic Jahn-Teller distortions become static. Also, the superconducting gap symmetry changesto isotropic S-Wave. An isotropic gap is more favorable for increasing the critical currentdensity, Jc.We propose a materials synthesis pathway for ???freezing??? the Jahn-Teller distortions in cupratesin order to increase the transition temperature, Tc, by mixing hole and electron dopants inYBCO. Initially, the Tc will not increase until the superconducting gap symmetry changes fromD-Wave to S-Wave. In addition to the standard superconducting characterization techniques, wewill use the room-temperature thermopower, the skin-depth, the superconducting surfaceimpedance, and the complex susceptibility to elucidate the relative positions of the hole andelectron dopants in our samples and thereby the amount of ???freezing??? that has occurred. Theoryand modeling will be used to interpret all measurements and provide guidance for the next roundof sample fabrication.Increasing the Tc or Jc of cuprates will be of enormous value to all Navy superconductingapplications.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2018
- Source ID
- N000141812679
Entities
People
- Carver Mead
Organizations
- California Institute of Technology
- Office of Naval Research
- United States Navy