Details of the disorder-induced transition between $s_{\pm }$ and $s_{++}$ states in two-band model for Fe-based superconductors

Abstract

Irradiation of superconductors with different particles is one of many ways to investigate effects of disorder. Here we study the disorder-induced transition between $s_{\pm }$ and $s_{++}$ states in two-band model for Fe-based superconductors with nonmagnetic impurities. Specifically, the important question of whether the superconducting gaps during the transition change smoothly or steeply? We show that the behavior can be of either type and is controlled by the ratio of intra- and interband impurity scattering and a parameter $\sigma$ that represents a scattering strength and changes from zero (Born approximation) to one (unitary limit). For the pure interband scattering potential and $\sigma \lesssim 0.11$, the $s_{\pm }\to s_{++}$ transition is accompanied by the steep behavior of gaps, while for larger values of $\sigma$, gaps change smoothly. The steep behavior of the gaps occurs at low temperatures, $T<0.1T_{c0}$, otherwise it is smooth. The critical temperature $T_c$ is always a smooth function of the scattering rate in spite of the steep changes in the behavior of the gaps.

8 pages, 5 figures, submitted to the Supercond. Sci. Technol. special issue on Irradiation Effects in Superconductors. arXiv admin note: text overlap with arXiv:1612.08683

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Cited by in corpus (4)

• Temperature-dependent $s_{\pm }\leftrightarrow s_{++}$ transitions in the multiband model for Fe-based superconductors with impurities
• Decisive proofs of the $s_{\pm }\to s_{++}$ transition in the temperature dependence of the magnetic penetration depth
• Thermodynamics of $s_{\pm }-to-s_{++}$ transition in iron pnictides in the vicinity of the Born limit
• Critical point of the transition between $s_{\pm }$ and $s_{++}$ states of a two-band superconductor with nonmagnetic impurities