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This work presents 75As NMR spin echo decay rate (1/T2) measurements in Ba(Fe1-xRhx)2As2 superconductors, for 0.041 < x < 0.094. It is shown that 1/T2 increases upon cooling, in the normal phase, suggesting the onset of an unconventional very low-frequency activated dynamic. The correlation times of the fluctuations and their energy barriers are derived. The motion is favored at large Rh content, while it is hindered by the application of a magnetic field perpendicular to the FeAs layers. The same dynamic is observed in the spin-lattice relaxation rate, in a quantitatively consistent manner. These results are discussed in the light of nematic fluctuations involving domain wall motion. The analogies with the behaviour observed in the cuprates are also outlined.
We investigated the elastic properties of the iron-based superconductor Ba(Fe1-xCox)2As2 with eight Co concentrations. The elastic constant C66 shows large elastic softening associated with the structural phase transition. The C66 was analyzed base o
The electronic structure of electron doped iron-arsenide superconductors Ba(Fe1- xCox)2As2 has been measured with Angle Resolved Photoemission Spectroscopy. The data reveal a marked photon energy dependence of points in momentum space where the bands
We present nuclear magnetic resonance evidence that very slow ($leq 1$ MHz) spin fluctuations persist into the overdoped regime of Ba(Fe$_{1-x}$Rh$_{x}$)$_2$As$_2$ superconductors. Measurements of the $^{75}$As spin echo decay rate, obtained both wit
Most iron-based superconductors are characterized by the s+- symmetry of their order parameter, and are expected to go through a transition to the s++ state if enough disorder is introduced. We previously reported the observation of this transition i
The evolution of 75As NMR parameters with composition and temperature was probed in the Ba(Fe1-xRux)2As2 system where Fe is replaced by isovalent Ru. While the Ru-end member was found to be a conventional Fermi liquid, the composition (x=0.5) corresp