Symmetry-decomposed elastoresistance of AFe2As2 (A = K, Rb, Cs)

We present elastoresistance measurements of the iron-based superconductors AFe2As2 (A = K, Rb, Cs) in the A1g, B1g and B2g symmetry channels. These materials have strong electronic correlations and show a crossover between a low-temperature coherent heavy Fermi liquid and a high-temperature regime of reduced quasiparticle coherence [1,2]. Neutralizing the large thermal expansion of these materials by means of a piezoelectric strain cell is found to be essential to obtaining intrinsic results. All three materials have a significant in-plane symmetric A1g response, consistent with the coherence-incoherence crossover.