AUTHOR=Hong Xiaochen , Sykora Steffen , Caglieris Federico , Behnami Mahdi , Morozov Igor , Aswartham Saicharan , Grinenko Vadim , Kihou Kunihiro , Lee Chul-Ho , Büchner Bernd , Hess Christian 

TITLE=Elastoresistivity of Heavily Hole-Doped 122 Iron Pnictide Superconductors

JOURNAL=Frontiers in Physics

VOLUME=Volume 10 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2022.853717

DOI=10.3389/fphy.2022.853717

ISSN=2296-424X

ABSTRACT=Nematicity in the heavily hole-doped iron pnictide superconductors remains controversial. Sizeable nematic fluctuations and even nematic orders far from a magnetic instability were declared in RbFe2As2 and its sister compounds. Here we report a systematic elastoresistance study of series of isovalent- and electron-doped KFe2As2 crystals. We found divergent elastoresistance upon cooling for all the crystals along their [110] direction. The amplitude of elastoresistivity diverges if K is substituted with larger ions or if the system is driven towards a Lifshitz transition. However, we conclude none of them necessarily indicates an independent nematic critical point. Instead, the increased nematicity can be associated with another electronic criticality. In particular, we propose a mechanism how elastoresistivity is enhanced at a Lifshitz transition.