Canted antiferromagnetism in high-purity NaFeF3 prepared by a novel wet-chemical synthesis method

We report a synthesis method, and structural and magnetic characterization, for the fluoroperovskite NaFeF3. We have developed a wet-chemical method that allows preparation of large volumes of air-sensitive luoroperovskites with high purity. NaFeF3 has a Néel temperature (TN ) of 90 K and a Weiss constant (θ) of −124 K, corresponding to dominant antiferromagnetic interactions. Below TN , a slight difference is observed between zero-field and field-cooled samples, indicating spin canting and weak ferromagnetism. AC magnetometry supports that weak erromagnetism is inherent to NaFeF3 and not due to an impurity. From powder neutron diffraction data, we describe the magnetic structure precisely as a weakly canted G-type (magnetic space group Pnma). A ferromagnetic component is allowed in Pnma, however, this component is too small to be confirmed on the basis of powder neutron diffraction data and may be absent in zero magnetic fields.