Disorder-induced topological change of the superconducting gap structure in iron pnictides

Abstract

In superconductors with unconventional pairing mechanisms, the energy gap in the excitation spectrum often has nodes, which allow quasiparticle excitations at low energies. In many cases, e.g. $d$-wave cuprate superconductors, the position and topology of nodes are imposed by the symmetry, and thus the presence of gapless excitations is protected against disorder. Here we report on the observation of distinct changes in the gap structure of iron-pnictide superconductors with increasing impurity scattering. By the successive introduction of nonmagnetic point defects into BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$ crystals via electron irradiation, we find from the low-temperature penetration depth measurements that the nodal state changes to a nodeless state with fully gapped excitations. Moreover, under further irradiation the gapped state evolves into another gapless state, providing bulk evidence of unconventional sign-changing $s$-wave superconductivity. This demonstrates that the topology of the superconducting gap can be controlled by disorder, which is a strikingly unique feature of iron pnictides.

5 pages, 4 figures

References in corpus (8)

• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Magnetic Penetration Depth in Unconventional Superconductors
• A Sharp Peak of the Zero-Temperature Penetration Depth at Optimal Composition in BaFe2(As1-xPx)2
• Microwave Surface-Impedance Measurements of the Magnetic Penetration Depth in Single Crystal Ba1-xKxFe2As2 Superconductors: Evidence for a Disorder-Dependent Superfluid Density
• Origin of Gap Anisotropy in Spin Fluctuation Models of the Fe-pnictides
• Lifting of nodes by disorder in extended-$s$ state superconductors: application to ferropnictides
• Magnetic penetration depth of single crystal SmFeAsO_{1-x}F_y: a fully gapped superconducting state
• Universal pair-breaking in transition metal-substituted iron-pnictide superconductors

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