Evidence for superconducting gap nodes in the zone-centered hole bands of KFe2As2 from magnetic penetration-depth measurements

K. Hashimoto; A. Serafin; S. Tonegawa; R. Katsumata; R. Okazaki; T. Saito; H. Fukazawa; Y. Kohori; K. Kihou; C. H. Lee; A. Iyo; H. Eisaki; H. Ikeda; Y. Matsuda; A. Carrington; T. Shibauchi

doi:10.1103/physrevb.82.014526

arXiv · 1003.6022

Evidence for superconducting gap nodes in the zone-centered hole bands of KFe2As2 from magnetic penetration-depth measurements

K. Hashimoto·A. Serafin·S. Tonegawa·R. Katsumata·R. Okazaki·T. Saito·H. Fukazawa·Y. Kohori·K. Kihou·C. H. Lee·A. Iyo·H. Eisaki·H. Ikeda·Y. Matsuda·A. Carrington·T. Shibauchi

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Abstract

Among the iron-based pnictide superconductors the material KFe$_2$As$_2$ is unusual in that its Fermi surface does not consist of quasi-nested electron and hole pockets. Here we report measurements of the temperature dependent London penetration depth of very clean crystals of this compound with residual resistivity ratio $>1200$. We show that the superfluid density at low temperatures exhibits a strong linear-in-temperature dependence which implies that there are line nodes in the energy gap on the large zone-centered hole sheets. The results indicate that KFe$_2$As$_2$ is an unconventional superconductor with strong electron correlations.

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K. Hashimoto, A. Serafin, S. Tonegawa, R. Katsumata, R. Okazaki, T. Saito, H. Fukazawa, Y. Kohori, K. Kihou, C. H. Lee, A. Iyo, H. Eisaki, H. Ikeda, Y. Matsuda, A. Carrington, T. Shibauchi. 2010-03-31. Evidence for superconducting gap nodes in the zone-centered hole bands of KFe2As2 from magnetic penetration-depth measurements. https://doi.org/10.1103/physrevb.82.014526

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