Absence of nematic instability in LiFeAs
Michael Wissmann, Federico Caglieris, Xiaochen Hong, Saicharan Aswartham, Anna Vorobyova, Igor Morozov, Bernd Büchner, Christian Hess
The relationship between unconventional superconductivity, antiferromagnetism
and nematic order in iron-based superconductors (FeSCs) is still highly
debated. In many FeSCs superconductivity is in proximity of a nematically and
magnetically ordered state. LiFeAs is an exceptional stoichiometric FeSC
becoming superconducting below 18 K, without undergoing a structural or
magnetic transition. However, some recent experimental studies suggested the
existence of finite nematic fluctuations and even a nematic superconducting
state. In this study, we employ elastoresistance as a measure of nematic
fluctuations in pristine LiFeAs and compare the findings with the
elastoresistance of LiFeAs at low Co and V doping levels as well with that of
magnetically and nematically ordering NaFeAs. We find LiFeAs and cobalt-doped
LiFeAs far away from a nematic instability.