Impurity-induced bound states inside the superconducting gap of FeSe

Abstract

We investigate the local density of states in the vicinity of a native dumbbell defect arising from an Fe vacancy in FeSe single crystals. The tunneling spectra close to the impurity display two bound states inside the superconducting gap, equally spaced with respect to zero energy but asymmetric in amplitude. Using spin-polarized density functional theory (DFT) calculations on realistic slab models with Fe vacancy, we show that such a defect does not induce a local magnetic moment. Therefore, the dumbbell defect is considered as non-magnetic. Thus, the in-gap bound states emerging from a non-magnetic defect-induced pair-breaking suggest a sign changing pairing state in this material.

8 pages, 6 figures

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Cited by in corpus (8)

• Nematicity, magnetism and superconductivity in FeSe
• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe
• Disorder-robust high-field superconducting phase of FeSe single crystals
• Stoichiometry and defect superstructures in epitaxial FeSe films on SrTiO3
• Impurity induced magnetic ordering in Sr${}_2$RuO${}_4$
• Atomic-scale analysis of disorder by similarity learning from tunneling spectroscopy
• Impact of Disorder on the Superconducting Properties and BCS-BEC Crossover in FeSe Single Crystals