Persistence of slow fluctuations in the overdoped regime of Ba(Fe1-xRhx)2As2 superconductors

We present nuclear magnetic resonance evidence that very slow (<= 1 MHz) spin fluctuations persist into the overdoped regime of Ba(Fe1-xRhx)(2)As-2 superconductors. Measurements of the As-75 spin echo decay rate, obtained both with Hahn Echo and Carr Purcell Meiboom Gill pulse sequences, show that the slowing down of spin fluctuations can be described by short-range diffusive dynamics, likely involving domain walls motions separating (pi/a, 0) from (0, pi/a) correlated regions. This slowing down of the fluctuations is weakly sensitive to the external magnetic field and, although fading away with doping, it extends deeply into the overdoped regime.