Small-q phonon mediated singlet and chiral spin triplet superconductivity in LiFeAs

2013/03/09 by A. Aperis, Aperis, A., G. Varelogiannis +1
Physics and Astronomy · #FOS: Physical sciences #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con

paper · pdf · doi:10.48550/arxiv.1303.2231

4.5 pages, 3 figures, 1 table + 4 pages supplementary material

arxiv created 2013/03/09 · arxiv updated 2013/03/12

Abstract

We report fully momentum dependent, self-consistent calculations of the gap symmetry, Fermi surface (FS) anisotropy and Tc of superconducting (SC) LiFeAs using the experimental band structure and a realistic small-q electron phonon interaction within the framework of Migdal-Eliashberg theory. In the stoichiometric regime, we find the exact s++ gap as reported by ARPES. For slight deviations from stoichiometry towards electron doping, we find that a chiral triplet p_x+ip_y state stabilizes near Tc and that at lower temperatures a transition from the triplet to singlet s+- SC takes place. Further doping stabilizes the chiral p-wave SC down to T=0. Precisely the same behavior was observed recently by NMR. Our results provide a natural and universal understanding of the conflicting experimental observations in LiFeAs.

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