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arXiv · 0903.4362

Momentum-resolved superconducting gap in the bulk of Ba$_{1-x}$K$_{x}$Fe$_2$As$_2$ from combined ARPES and $μ$SR measurements

D. V. Evtushinsky·D. S. Inosov·V. B. Zabolotnyy·M. S. Viazovska·R. Khasanov·A. Amato·H. -H. Klauss·H. Luetkens·Ch. Niedermayer·G. L. Sun·V. Hinkov·C. T. Lin·A. Varykhalov·A. Koitzsch·M. Knupfer·B. Büchner·A. A. Kordyuk·S. V. Borisenko
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Abstract

Here we present a calculation of the temperature-dependent London penetration depth, $λ(T)$, in Ba$_{1-x}$K$_{x}$Fe$_2$As$_2$ (BKFA) on the basis of the electronic band structure [1,2] and momentum-dependent superconducting gap [3] extracted from angle-resolved photoemission spectroscopy (ARPES) data. The results are compared to the direct measurements of $λ(T)$ by muon spin rotation ($μ$SR) [4]. The value of $λ(T=0)$, calculated with \emph{no} adjustable parameters, equals 270 nm, while the directly measured one is 320 nm; the temperature dependence $λ(T)$ is also easily reproduced. Such agreement between the two completely different approaches allows us to conclude that ARPES studies of BKFA are bulk-representative. Our review of the available experimental studies of the superconducting gap in the new iron-based superconductors in general allows us to state that all hole-doped of them bear two nearly isotropic gaps with coupling constants $2Δ/k_{\rm B}T_{\rm c}=2.5\pm1.5$ and $7\pm2$.

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D. V. Evtushinsky, D. S. Inosov, V. B. Zabolotnyy, M. S. Viazovska, R. Khasanov, A. Amato, H. -H. Klauss, H. Luetkens, Ch. Niedermayer, G. L. Sun, V. Hinkov, C. T. Lin, A. Varykhalov, A. Koitzsch, M. Knupfer, B. Büchner, A. A. Kordyuk, S. V. Borisenko. 2009-03-25. Momentum-resolved superconducting gap in the bulk of Ba$_{1-x}$K$_{x}$Fe$_2$As$_2$ from combined ARPES and $μ$SR measurements. https://doi.org/10.1088/1367-2630%2F11%2F5%2F055069

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