MgB2 energy gap determination by scanning tunnelling spectroscopy

We report scanning tunnelling spectroscopy (STS) measurements of the gap properties of both ceramic MgB2 and c-axis oriented epitaxial MgB2 thin films. Both show a temperature dependent zero bias conductance peak and evidence for two superconducting gaps. We report tunnelling spectroscopy of superco...

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Bibliographic Details
Main Authors: Heitmann, T, Bu, S, Kim, D, Choi, J, Giencke, J, Eom, C, Regan, K, Rogado, N, Hayward, M, He, T, Slusky, J, Khalifah, P, Haas, M, Cava, R, Larbalestier, D, Rzchowski, MS
Format: Journal article
Language:English
Published: 2004
Description
Summary:We report scanning tunnelling spectroscopy (STS) measurements of the gap properties of both ceramic MgB2 and c-axis oriented epitaxial MgB2 thin films. Both show a temperature dependent zero bias conductance peak and evidence for two superconducting gaps. We report tunnelling spectroscopy of superconductor-insulator-superconductor (S-I-S) junctions formed in two ways in addition to normal metal-insulator-superconductor (N-I-S) junctions. We find a gap Δ = 2.2-2.8 meV, with spectral features and temperature dependence that are consistent between S-I-S junction types. In addition, we observe evidence of a second, larger gap, Δ = 7.2 meV, consistent with a proposed two-hand model.