  We study the characteristic time scales of the fluctuating local moments in
Hund's metal systems for different degrees of correlation. By analyzing the
dynamical spin susceptibility in the real-time domain via the
fluctuation-dissipation theorem, we determine the time scales controlling
oscillation and damping of on-site fluctuations - a crucial factor for the
detection of local moments with different experimental probes. We apply this
procedure to realistic many-body calculations of different families of
iron-pnictides and chalcogenides, explaining the material-specific trend in the
discrepancies reported between experimental and theoretical estimates of the
magnetic moments.
