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arXiv · 1403.1027

Observation of a Robust Zero-energy Bound State in Iron-based Superconductor Fe(Te,Se)

J. -X. Yin·Zheng Wu·J. -H. Wang·Z. -Y. Ye·Jing Gong·X. -Y. Hou·Lei Shan·Ang Li·X. -J. Liang·X. -X. Wu·Jian Li·C. -S. Ting·Z. Wang·J. -P. Hu·P. -H. Hor·H. Ding·S. H. Pan
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Abstract

A robust zero-energy bound state (ZBS) in a superconductor, such as a Majorana or Andreev bound state, is often a consequence of non-trivial topological or symmetry related properties, and can provide indispensable information about the superconducting state. Here we use scanning tunneling microscopy/spectroscopy to demonstrate, on the atomic scale, that an isotropic ZBS emerges at the randomly distributed interstitial excess Fe sites in the superconducting Fe(Te,Se). This ZBS is localized with a short decay length of ~ 10 Å, and surprisingly robust against a magnetic field up to 8 Tesla, as well as perturbations by neighboring impurities. We find no natural explanation for the observation of such a robust zero-energy bound state, indicating a novel mechanism of impurities or an exotic pairing symmetry of the iron-based superconductivity.

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J. -X. Yin, Zheng Wu, J. -H. Wang, Z. -Y. Ye, Jing Gong, X. -Y. Hou, Lei Shan, Ang Li, X. -J. Liang, X. -X. Wu, Jian Li, C. -S. Ting, Z. Wang, J. -P. Hu, P. -H. Hor, H. Ding, S. H. Pan. 2014-03-05. Observation of a Robust Zero-energy Bound State in Iron-based Superconductor Fe(Te,Se). https://doi.org/10.1038/nphys3371

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