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A molecular magnet vertical tunnel junction.

ORAL

Abstract

We have fabricated EGaIn/CoPc/ITO heterojunctions where sublimated CoPc films as thin as 5~nm are sandwiched between transparent bottom-layer ITO and top-layer soft-landing eutectic GaIn (EGaIn) electrodes. Roughness of the CoPc films was determined by AFM to be 1.6~nm, and crystalline ordering of lying-down planar molecules was confirmed by XRD. The current-voltage characteristics of the 5~nm thick sample reveal the onset of a superconducting gap below Tc~at~6~K (the transition temperature of metastable $\beta $-Ga in the EGaIn contact) thereby providing incontrovertible evidence for direct quantum mechanical tunneling processes through the magnetic molecules in our heterojunctions. Simmons' model fits of the conductance data to temperatures as high as 200~K with a weakly temperature-dependent tunnel barrier height near 1.6~eV are consistent with this interpretation. Voltage dependent features in the differential conductance measurements may relate to spin states of single molecules or aggregates of molecules and prove to be important for quantum information device development.

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Authors

  • Xuanyuan Jiang

    University of Florida

  • Andrew Brooks

    University of Florida

  • Duy Le

    University of Central Florida

  • Robert Grzywacz

    Moscow Institute of Physics and Technology, University of Virginia, California Institute of Technology, National High Magnetic Field Laboratory, University and Student Affairs; Oak Ridge Laboratory, Brookhaven National Laboratory, Physicist, Brookhaven National Laboratory, Oak Ridge National Laboratory, USA, Center for Nuclear Study, University of Tokyo, Advanced Science Research Center, Japan Atomic Energy Agency, Florida State University, Presidency University, Kolkata, INDIA, VECC,Kolkata, INDIA, SINP,Kolkata, INDIA, UGC-DAE CSR (Kolkata), INDIA, IFIN-HH, ELI-NP, Romania, Variable Energy Cyclotron Centre,Kolkata, INDIA, IEM, Kolkata, India, Victoria Institution (College), Kolkata, INDIA, Variable Energy Cyclotron Centre, Kolkata, INDIA, NHMFL; Florida State University, FAMU-FSU College of Engineering, Florida State University, Physics Department, Florida State University, Mississippi State University, NHMFL-FSU, U. Colorado at Boulder, NHMFL, University of Alabama at Birmingham, Oak Ridge National Laboratory, Argonne National Laboratory, Alabama School of Math and Science, University of South Alabama, University of Florida, University of Notre Dame, University of Texas at Dallas, Bob Jones University, University of Tennessee at Chattanooga, The Autonomous University of San Luis Potosí, Northern Arizona University, Flagstaff, AZ, Harvard-Smithsonian Center for Astrophysics, Cambridge, National Institute of Standards and Technology, Clemson University, University of South Florida, Phenikaa University, University of Ulsan, Ohio University, University of Hawaii, University of California, Davis, University of California, Davis., Saleh Research Centre, Department of Physics, Florida State university, Tallahassee, FL32306, USA, WestCHEM, School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK, Professor, facility manager, Student, Florida State University(Former), Hebrew University, Israel \& Ioffe Institute, St.\ Petersburg, Russia, University of Tennessee, Knoxville

  • John KOPTUR-PALENCHAR

    University of Florida

  • Robert Grzywacz

    Moscow Institute of Physics and Technology, University of Virginia, California Institute of Technology, National High Magnetic Field Laboratory, University and Student Affairs; Oak Ridge Laboratory, Brookhaven National Laboratory, Physicist, Brookhaven National Laboratory, Oak Ridge National Laboratory, USA, Center for Nuclear Study, University of Tokyo, Advanced Science Research Center, Japan Atomic Energy Agency, Florida State University, Presidency University, Kolkata, INDIA, VECC,Kolkata, INDIA, SINP,Kolkata, INDIA, UGC-DAE CSR (Kolkata), INDIA, IFIN-HH, ELI-NP, Romania, Variable Energy Cyclotron Centre,Kolkata, INDIA, IEM, Kolkata, India, Victoria Institution (College), Kolkata, INDIA, Variable Energy Cyclotron Centre, Kolkata, INDIA, NHMFL; Florida State University, FAMU-FSU College of Engineering, Florida State University, Physics Department, Florida State University, Mississippi State University, NHMFL-FSU, U. Colorado at Boulder, NHMFL, University of Alabama at Birmingham, Oak Ridge National Laboratory, Argonne National Laboratory, Alabama School of Math and Science, University of South Alabama, University of Florida, University of Notre Dame, University of Texas at Dallas, Bob Jones University, University of Tennessee at Chattanooga, The Autonomous University of San Luis Potosí, Northern Arizona University, Flagstaff, AZ, Harvard-Smithsonian Center for Astrophysics, Cambridge, National Institute of Standards and Technology, Clemson University, University of South Florida, Phenikaa University, University of Ulsan, Ohio University, University of Hawaii, University of California, Davis, University of California, Davis., Saleh Research Centre, Department of Physics, Florida State university, Tallahassee, FL32306, USA, WestCHEM, School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK, Professor, facility manager, Student, Florida State University(Former), Hebrew University, Israel \& Ioffe Institute, St.\ Petersburg, Russia, University of Tennessee, Knoxville

  • Khalil Abboud

    University of Florida

  • RICHARD HENNIG

    University of Florida

  • Talat Rahman

    University of Central Florida

  • Xiaoguang Zhang

    University of Florida

  • Arthur Hebard

    University of Florida