| Итог: | We report a de Haas-van Alphen oscillation study of the 111 iron pnictide superconductors LiFeAs with T c18K and LiFeP with T c5K. We find that for both compounds the Fermi surface topology is in good agreement with density functional band-structure calculations and has almost nested electron and hole bands. The effective masses generally show significant enhancement, up to ∼3 for LiFeP and ∼5 for LiFeAs. However, one hole Fermi surface in LiFeP shows a very small enhancement, as compared with its other sheets. This difference probably results from k-dependent coupling to spin fluctuations and may be the origin of the different nodal and nodeless superconducting gap structures in LiFeP and LiFeAs, respectively. © 2012 American Physical Society.
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