Andreev Reflection Spectra of $d$-wave Superconductors

ORAL

Abstract

At a normal metal/superconductor interface Andreev reflection occurs, which can be utilized to measure spin polarization of the normal metal and also the superconducting gap of the superconductor. An $s$-wave superconductor has an isotropic gap and for an unpolarized current the Andreev reflection spectrum within the gap is twice that of outside the gap. A fully spin polarized current suppresses the Andreev reflection therefore causes zero conductance within the gap. The scenario is quite different in a $d$-wave superconductor because the order parameter has anisotropy and phase. In this work, we calculate Andreev Reelection spectra of an interface between a normal metal and a $d$-wave superconductor for a current with any polarization, based on the recent Chen-Tesanovic-Chien (CTC) model. It is shown that the point angle of the interface can drastically change the Andreev spectra and a zero bias anomaly (ZBA) is observed in the tunneling regime only if the point angle is large. The spin polarization can also drastically affect the spectra and can completely suppress the ZBA. Our calculation shows that one can use both the spin polarization and the point angle to verify the ZBA in unconventional superconductors.

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Authors

  • Charles Snider

    Arizona State University

  • Norm Buchanan

    Brigham Young University, Stanford University, University of Central Florida, NCAR/High Altitude Observatory, Arizona Vitro-retinal consultants, University of Michigan, Arizona State University, University of Denver, Arizona State University Dept of Physics, Arizona State University Dept of Chemistry and Biochemistry, LASP, University of Colorado Boulder, Center for Atmospheric and Space Science, Utah State University, Dixie State College, Utah, USU Materials Physics Group, UVU Physics Department, Box Elder Innovations, Space Telescope Science Institute, Northern Kentucky University, Retired, Utah Valley University, Univ. of California, Los Angelos, Colorado State University, St. Petersburg Electro-technical University, Universidad Nacional Aut\'onoma de M\'exico, New Mexico State University, University of New Mexico, University of Wurtzberg, Theoretical Division, Los Alamos National Laboratory, National High Magnetic Field Laboratory, LANL, UCLA, Max-planck-Institut f\"{u}r Astronomie, W. M. Keck Observatory, University of Arizona, Nuclear Physics Group, Brigham Young University, GLOBALFOUNDRIES, IBM Systems and Technology Group, IBM Research Division, T.J. Watson Research Center, Sandia National Laboratory, NMSU, Military University of Technology, Warsaw, Poland, James Franck Institute and Department of Physics, University of Chicago, Department of Atmospheric Sciences, University of Washington, JISAO, University of Washington, New Mexico Institute of Mining and Technology, NorthWest Research Associates, University of Alaska, Fairbanks, Utah State University, New Mexico Tech, University of Cambridge, Los Alamos National Laboratory, RAPTOR Science, Institute of Space and Astronomical Science, Japanese Aerospace Exploration Agency, Weber State University, Department of Physics, New Mexico State University, BYU Physics, Physics Department, University of Arizona, ABQMR, University of Colorado at Boulder, SNL and CINT, Los Alamos National Lab, Center for Quantum Information and Control, University of Arizona, Center for Quantum Information and Control, University of New Mexico, University of Calgary, Colorado School of Mines

  • Norm Buchanan

    Brigham Young University, Stanford University, University of Central Florida, NCAR/High Altitude Observatory, Arizona Vitro-retinal consultants, University of Michigan, Arizona State University, University of Denver, Arizona State University Dept of Physics, Arizona State University Dept of Chemistry and Biochemistry, LASP, University of Colorado Boulder, Center for Atmospheric and Space Science, Utah State University, Dixie State College, Utah, USU Materials Physics Group, UVU Physics Department, Box Elder Innovations, Space Telescope Science Institute, Northern Kentucky University, Retired, Utah Valley University, Univ. of California, Los Angelos, Colorado State University, St. Petersburg Electro-technical University, Universidad Nacional Aut\'onoma de M\'exico, New Mexico State University, University of New Mexico, University of Wurtzberg, Theoretical Division, Los Alamos National Laboratory, National High Magnetic Field Laboratory, LANL, UCLA, Max-planck-Institut f\"{u}r Astronomie, W. M. Keck Observatory, University of Arizona, Nuclear Physics Group, Brigham Young University, GLOBALFOUNDRIES, IBM Systems and Technology Group, IBM Research Division, T.J. Watson Research Center, Sandia National Laboratory, NMSU, Military University of Technology, Warsaw, Poland, James Franck Institute and Department of Physics, University of Chicago, Department of Atmospheric Sciences, University of Washington, JISAO, University of Washington, New Mexico Institute of Mining and Technology, NorthWest Research Associates, University of Alaska, Fairbanks, Utah State University, New Mexico Tech, University of Cambridge, Los Alamos National Laboratory, RAPTOR Science, Institute of Space and Astronomical Science, Japanese Aerospace Exploration Agency, Weber State University, Department of Physics, New Mexico State University, BYU Physics, Physics Department, University of Arizona, ABQMR, University of Colorado at Boulder, SNL and CINT, Los Alamos National Lab, Center for Quantum Information and Control, University of Arizona, Center for Quantum Information and Control, University of New Mexico, University of Calgary, Colorado School of Mines

  • Norm Buchanan

    Brigham Young University, Stanford University, University of Central Florida, NCAR/High Altitude Observatory, Arizona Vitro-retinal consultants, University of Michigan, Arizona State University, University of Denver, Arizona State University Dept of Physics, Arizona State University Dept of Chemistry and Biochemistry, LASP, University of Colorado Boulder, Center for Atmospheric and Space Science, Utah State University, Dixie State College, Utah, USU Materials Physics Group, UVU Physics Department, Box Elder Innovations, Space Telescope Science Institute, Northern Kentucky University, Retired, Utah Valley University, Univ. of California, Los Angelos, Colorado State University, St. Petersburg Electro-technical University, Universidad Nacional Aut\'onoma de M\'exico, New Mexico State University, University of New Mexico, University of Wurtzberg, Theoretical Division, Los Alamos National Laboratory, National High Magnetic Field Laboratory, LANL, UCLA, Max-planck-Institut f\"{u}r Astronomie, W. M. Keck Observatory, University of Arizona, Nuclear Physics Group, Brigham Young University, GLOBALFOUNDRIES, IBM Systems and Technology Group, IBM Research Division, T.J. Watson Research Center, Sandia National Laboratory, NMSU, Military University of Technology, Warsaw, Poland, James Franck Institute and Department of Physics, University of Chicago, Department of Atmospheric Sciences, University of Washington, JISAO, University of Washington, New Mexico Institute of Mining and Technology, NorthWest Research Associates, University of Alaska, Fairbanks, Utah State University, New Mexico Tech, University of Cambridge, Los Alamos National Laboratory, RAPTOR Science, Institute of Space and Astronomical Science, Japanese Aerospace Exploration Agency, Weber State University, Department of Physics, New Mexico State University, BYU Physics, Physics Department, University of Arizona, ABQMR, University of Colorado at Boulder, SNL and CINT, Los Alamos National Lab, Center for Quantum Information and Control, University of Arizona, Center for Quantum Information and Control, University of New Mexico, University of Calgary, Colorado School of Mines