Suppression of the nuclear forward scattering signal in GdBaFe2O5 and PrBaFe2O5

Abstract Antiferromagnetic double-cell perovskites GdBaFe2O5.004 and PrBaFe2O5.001 were studied with 14.4 keV 57Fe nuclear forward scattering (NFS). Both have charge- and orbital-ordered iron below a Verwey transition temperature T V and valence-mixed iron above a second transition at a higher T p . At intermediate temperatures T V T T p , only a partial charge separation remains and more than 75% of the NFS signal is suppressed. The breakdown of the coherent signal is due to broadening of the nuclear resonance by local disorder of the two partially charge-separated iron species at the single crystallographic Fe site.