Temperature dependence of the penetration depth in pnictides measured locally with scanning SQUIDs

ORAL

Abstract

Using a Scanning SQUID Microscope, we locally measure changes in the ab-plane penetration depth $\Delta\lambda_{ab}(T)$ of superconducting samples. Local measurements allow us to check for electronic homogeneity, including $T_c$ homogeneity, as well as to minimize the possibility of sample-geometry-dependent errors, including contributions from the c-axis penetration depth. We report results on lead as well as on pnictide superconductors, including $Ba(Fe_{0.95}Co_{0.05})_{2}As_{2}$ and LaFePO. In LaFePO, we find a linear-T dependence with a slope of 143$\pm$15 {\AA}/K, suggesting well-developed line nodes in the superconducting order parameter.

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Authors

  • Thomas M. Lippman

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA., Stanford University

  • Clifford Hicks

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.

  • Lan Luan

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA., Stanford University

  • Martin E. Huber

    Departments of Physics and Electrical Engineering, University of Colorado Denver, Denver, Colorado, 80217, USA., University of Colorado Denver

  • James Analytis

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA., GLAM, Stanford University, Ca 94304, Stanford University

  • Jiun-Haw Chu

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA., Stanford University

  • Ann Erickson

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.

  • Ian Fisher

    Stanford, Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA., GLAM, Stanford University, Ca 94304, Stanford University

  • Kathryn A. Moler

    Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA., Stanford University