Figure 3

X-Band ESR lines at T = 150 K for powdered crystals of BaFe_1.9M_0.1As₂ (M = Cu, Mn) and BaFe_1.895Mn_0.005Co_0.1As₂.

The spectra were normalized by the concentration of paramagnetic probes in order to clearly compare their intensities. The solid lines are Lorentzian fits to the spectra (sample grain size smaller than the skin depth⁴⁸). It is worth mentioning that, in order to obtain the ESR signal, the sample surface must be completely clean and free of In-flux. The ESR signals for both samples were calibrated at 300 K using a strong pitch standard sample with 4.55 × 10¹⁵ spins/cm.