Controlled Quantized Conductance Steps Using a Simple Mechanical System: An Undergraduate Lab Experiment

ORAL

Abstract

We demonstrate clear quantized conductance steps in mechanical break junctions (MBJ) based on a gold wire, a springy-steel bending beam, a micrometer, a 1.5V battery , and a Teflon disc that we rotate manually. The voltage across the wire is measured using a NI-DAQ assistant unit and a simple LabVIEW program. As the wire is stretched, its resistance (i.e. voltage across it) increases gradually then follows a stair-case- like shape, which is a hallmark of quantized conductance, with steps at values of 25.8 k$\Omega $/2n, where n is an integer. The resistance jumps are clearer and more distinct for smaller n and become closer for larger n, which is a demonstration of the Correspondence Principle. The quantization occurs when the wire is thin enough that its diameter is comparable to the de Broglie wave length of the current-carrying electrons and is a direct consequence of confinement. This experiment is designed for sophomore/junior level undergraduate labs.

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Authors

  • Dale Igram

    Cornell University, Air Force Research Labs, The Center for Photochemical Sciences and Department of Physics, BGSU, Department of Physics, BGSU, Department of Physics and Astronomy, Ball State University, Miami University, Johannes-Gutenberg-Universitat, Mainz, Germany, Martin-Luther-Universitat, Halle, Germany, The Ohio State University, Department of Physics, Columbus, OH 43210, USA, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, Ohio Northern University, The Ohio State University, Department of Physics, Columbus, OH 43210, Sciprint.org, Ball State University, Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, PA 16802

  • Dale Igram

    Cornell University, Air Force Research Labs, The Center for Photochemical Sciences and Department of Physics, BGSU, Department of Physics, BGSU, Department of Physics and Astronomy, Ball State University, Miami University, Johannes-Gutenberg-Universitat, Mainz, Germany, Martin-Luther-Universitat, Halle, Germany, The Ohio State University, Department of Physics, Columbus, OH 43210, USA, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, Ohio Northern University, The Ohio State University, Department of Physics, Columbus, OH 43210, Sciprint.org, Ball State University, Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, PA 16802

  • Dale Igram

    Cornell University, Air Force Research Labs, The Center for Photochemical Sciences and Department of Physics, BGSU, Department of Physics, BGSU, Department of Physics and Astronomy, Ball State University, Miami University, Johannes-Gutenberg-Universitat, Mainz, Germany, Martin-Luther-Universitat, Halle, Germany, The Ohio State University, Department of Physics, Columbus, OH 43210, USA, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, Ohio Northern University, The Ohio State University, Department of Physics, Columbus, OH 43210, Sciprint.org, Ball State University, Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, PA 16802

  • Dale Igram

    Cornell University, Air Force Research Labs, The Center for Photochemical Sciences and Department of Physics, BGSU, Department of Physics, BGSU, Department of Physics and Astronomy, Ball State University, Miami University, Johannes-Gutenberg-Universitat, Mainz, Germany, Martin-Luther-Universitat, Halle, Germany, The Ohio State University, Department of Physics, Columbus, OH 43210, USA, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, Ohio Northern University, The Ohio State University, Department of Physics, Columbus, OH 43210, Sciprint.org, Ball State University, Department of Physics and Materials Research Institute, Pennsylvania State University, University Park, PA 16802