Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 53: Superconductivity: Fe-based Superconductors - 122

TT 53.12: Talk

Wednesday, April 2, 2014, 12:30–12:45, HSZ 201

Tracing the s_± symmetry in iron pnictides — •Micha Schilling¹, Sina Zapf¹, Boris Gorshunov^1,2,3, Andreas Baumgartner¹, Kazumasa Iida⁴, Valery A. Dravin⁵, Kirill V. Mitsen⁵, Dimitri Efremov⁶, Oleg Dolgov⁷, and Martin Dressel¹ — ¹1. Physikalisches Institut, Universität Stuttgart, Germany — ²Institute of General Physics, RAS, Russia — ³Moscow Institute of Physics and Technology, Russia — ⁴Institut für Metallische Werkstoffe, IFW Dresden, Germany — ⁵Lebedev Physical Institute, Moscow, 119991 Russia — ⁶Institute for theoretical physics, IFW, Dresden — ⁷Max-Planck Institut für Festkörperforschung, Stuttgart, Germany

For multiband iron pnictides, the symmetry of the superconducting order parameter is still under debate. It was suggested [1] that in the case of s_± symmetry, a disorder-induced crossover from s_± to s₊₊ symmetry could occur, meaning that the smaller superconducting gap Δ₁ first closes and then reopens. To that end, we have step-wise irradiated a Ba(Fe_0.9Co_0.1)₂As₂ thin film with protons and measured its complex conductivity in the terahertz frequency range. Our preliminary results show that the irradiation with protons is capable to linearly decrease the critical temperature of the film, while Δ₁ gets suppressed faster. Thus, further irradiation might reveal the reopening of Δ₁ and thus proof the s_± symmetry of the superconducting order parameter.
D.V. Efremov et al., Phys. Rev. B 84, 180512 (2011)
B. Gorshunov et al., Phys. Rev. B 81, 060509 (2010)