Intrinsic spin resonance in iron pnictides

摘要

We report on ESR measurements in polycrystalline LaFeAsO and PrFeSbO and in single crystalline Mn-doped Ba(Fe0.975Mn0.025)2As2. The absorption spectrum can be described by a broad resonance line with Lorentzian lineshape. The intensity of the resonance absorption follows the temperature dependence of the dc-susceptibility and mirrors the spin-density wave anomaly, while the linewidth roughly agrees with the electrical resistivity.