  The nematic susceptibility of hole-doped Ba1-xKxFe2As2 and electron-doped
Ba(Fe1-xCox)2As2 iron-based superconductors is obtained from measurements of
the elastic shear modulus using a three-point bending setup in a capacitance
dilatometer. Nematic fluctuations, although weakened by doping, extend over the
whole superconducting dome in both systems, suggesting their close tie to
superconductivity. Evidence for quantum critical behavior of the nematic
susceptibility is, surprisingly, only found for Ba(Fe1-xCox)2As2, the system
with the lower maximal Tc value.
