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arXiv · 1107.4505

Nodeless vs nodal order parameters in LiFeAs and LiFeP superconductors

K. Hashimoto·S. Kasahara·R. Katsumata·Y. Mizukami·M. Yamashita·H. Ikeda·T. Terashima·A. Carrington·Y. Matsuda·T. Shibauchi
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Abstract

High-precision measurements of magnetic penetration depth $λ$ in clean single crystals of LiFeAs and LiFeP superconductors reveal contrasting low-energy quasiparticle excitations. In LiFeAs the low-temperature $λ(T)$ shows a flat dependence indicative of a fully gapped state, which is consistent with previous studies. In contrast, LiFeP exhibits a $T$-linear dependence of superfluid density $\propto λ^{-2}$, indicating a nodal superconducting order parameter. A systematic comparison of quasiparticle excitations in the 1111, 122, and 111 families of iron-pnictide superconductors implies that the nodal state is induced when the pnictogen height from the iron plane decreases below a threshold value of $\sim 1.33$\,Å.

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K. Hashimoto, S. Kasahara, R. Katsumata, Y. Mizukami, M. Yamashita, H. Ikeda, T. Terashima, A. Carrington, Y. Matsuda, T. Shibauchi. 2011-07-22. Nodeless vs nodal order parameters in LiFeAs and LiFeP superconductors. https://doi.org/10.1103/physrevlett.108.047003

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