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=10

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=<p>Nematicity in heavily hole-doped iron pnictide superconductors remains controversial. Sizeable nematic fluctuations and even nematic orders far from magnetic instability were declared in RbFe<sub>2</sub>As<sub>2</sub> and its sister compounds. Here, we report a systematic elastoresistance study of a series of isovalent- and electron-doped KFe<sub>2</sub>As<sub>2</sub> crystals. We found divergent elastoresistance on 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 toward a Lifshitz transition. However, we conclude that 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 for how elastoresistivity is enhanced at a Lifshitz transition.</p>