Observation of a robust zero-energy bound state in iron-based superconductor Fe(Te,Se)
By J.-X. Yin, Zheng Wu, J. Wang, Z. Ye, Jing Gong, Xing-yuan Hou, L. Shan, Ang Li, X. Liang, X.-X. Wu and 7 more. Nature Physics, 2014
211 citations recorded by the source corpus.
The symmetry of Cooper pairs in iron-based superconductors is an issue under continued investigation. A scanning tunnelling study of Fe(Te,Se) reveals a robust zero-energy bound state, providing evidence for a non-trivial pairing symmetry. In superconductors, electrons are paired and condensed into the ground state. An impurity can break the electron pairs into quasiparticles with energy states inside the superconducting gap. The characteristics of such in-gap states reflect accordingly the properties of the superconducting ground state1. A zero-energy in-gap state is particularly noteworthy, because it can be the consequence of non-trivial pairing symmetry1 or topology2,3. Here we use scanning tunnelling microscopy/spectroscopy to demonstrate that an isotropic zero-energy bound state with a decay length of ∼10 Å emerges at each interstitial iron impurity in superconducting Fe(Te,Se). More noticeably, this zero-energy bound state is robust against a magnetic field up to 8 T, as well as perturbations by neighbouring impurities. Such a spectroscopic feature has no natural explanation in terms of impurity states in superconductors with s-wave symmetry, but bears all the characteristics of the Majorana bound state proposed for topological superconductors2,3, indicating that the superconducting state and the scattering mechanism of the interstitial iron impurities in Fe(Te,Se) are highly unconventional.
Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials
View Paper: https://www.semanticscholar.org/paper/981d5a31b47ff721d523fd835cd44923a7855d9f
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Citations in the corpus
- Flat bands, strange metals and the Kondo effect (2023, unknown): “The localized electrons form local moments, understood in terms of the Hund’s rules of atomic physics, whereas the itinerant electrons form broad bands, well described by single-particle theories such as DFT.”
- Probing topological quantum matter with scanning tunnelling microscopy (2021, methodology): “Panel a adapted from REF.(38), Springer Nature Limited.”
- Robust and Clean Majorana Zero Mode in the Vortex Core of High-Temperature Superconductor (Li0.84Fe0.16)OHFeSe (2018, background): “However, there are intrinsic impurity effects of interstitial Fe and heavy Te doping [23,24].”