Local destruction of superconductivity by non-magnetic impurities in mesoscopic iron-based superconductors

• DOI: 10.1038/ncomms8614
• Publication Date: 2015-07-03T11:21:48Z
• Authors: Jun Li; Min Ji; Tobias Schwarz; Xiaoxing Ke; Gustaaf Van Tendeloo; Jie Yuan; Paulo J. Pereira; Ya Huang; Gufei Zhang; Hai-Luke Feng; Ya-Hua Yuan; Takeshi Hatano; Reinhold Kleiner; Dieter Koelle; Liviu F. Chibotaru; Kazunari Yamaura; Hua-Bing Wang; Pei-Heng Wu; Eiji Takayama-Mur...; Johan Vanacken; Victor V. Moshcha...
• Keywords: Physics; 0103 physical sciences; Engineering sciences. Technology; 01 natural sciences; Article

AbstractThe determination of the pairing symmetry is one of the most crucial issues for the iron-based superconductors, for which various scenarios are discussed controversially. Non-magnetic impurity substitution is one of the most promising approaches to address the issue, because the pair-breaking mechanism from the non-magnetic impurities should be different for various models. Previous substitution experiments demonstrated that the non-magnetic zinc can suppress the superconductivity of various iron-based superconductors. Here we demonstrate the local destruction of superconductivity by non-magnetic zinc impurities in Ba0.5K0.5Fe2As2 by exploring phase-slip phenomena in a mesoscopic structure with 119 × 102 nm2 cross-section. The impurities suppress superconductivity in a three-dimensional ‘Swiss cheese’-like pattern with in-plane and out-of-plane characteristic lengths slightly below ∼1.34 nm. This causes the superconducting order parameter to vary along abundant narrow channels with effective cross-section of a few square nanometres. The local destruction of superconductivity can be related to Cooper pair breaking by non-magnetic impurities.