paper

Evolution from nematics to nematics in heavily hole-doped iron-based superconductors

arXiv:1902.10729 · doi:10.1103/PhysRevLett.123.146402

Abstract

Recent experiments reported an unusual nematic behavior of heavily hole-doped pnictides FeAs, with alkali = Rb, Cs. In contrast to the nematic order of the parent FeAs compounds (with alkaline earth = Sr, Ba), characterized by unequal nearest-neighbor Fe-Fe bonds, in the hole-doped systems nematic order is observed in the channel, characterized by unequal next-nearest-neighbor Fe-Fe (diagonal Fe-As-Fe) bonds. In this work, using density functional theory, we attribute this behavior to the evolution of the magnetic ground state along the series FeAs, from single stripes for small to double stripes for large . Our simulations using the reduced Stoner theory show that fluctuations of Fe moments are essential for the stability of the double-stripe configuration. We propose that the change in the nature of the magnetic ground state is responsible for the change in the symmetry of the vestigial nematic order that it supports.

5 pages, 4 figures

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