Temperature independence of the dielectric constant in the antiferromagnetic iron intergrowth: Sr4Fe2.5O7.25(SO4)0.5
Résumé
The magnetic structure of the anisotropic compound Sr4Fe2.5O7.25(SO4)0.5 has been determined by means of neutron diffraction and Mossbauer spectroscopy. Spins are lying in the basal plan within an antiferromagnetic G type structure. Depending on which species (O2- or SO42-) is surrounding iron atoms, latter exhibit 15% of difference on their magnetic moment at 5 k. This is in agreement with the quantitative representation of the different magnetic contributions of the Mossbauer spectrum. The compound appears to be a good dielectric, without any transition between 5 K and 400 K and a dielectric constant which is mostly temperature independent. A significate sensitivity of εr to an external applied magnetic field is finally detected.