La doping effects in the coupling between localized and itinerant electronic states in EuFe₂As₂ probed by Eu²⁺ ESR

In this work we present an Electron Spin Resonance (ESR) study on La-doped EuFe₂As₂ aiming to further understand the coupling of localized spin states and itinerant electrons in these systems. The temperature dependence of the Eu²⁺ ESR linewidth, g-value and intensity was investigated for both monocrystalline and powdered samples. Our results confirm the suggestion of previous ESR experiments on the pure compound [1], that the SDW transition dramatically changes the coupling between localized and itinerant states. In addition, we found a peculiar dome like shape in the Eu²⁺ ESR linewidth temperature dependence for temperatures between T_SDW and T_N.