Magnetic structure and properties of Pb8FeIIFe2IIIF24: a 1-D ferrimagnetic chain compound exhibiting a spin-flop transition

Abstract The magnetic structure of Pb 8 Fe II Fe 2 III F 24 was solved starting from its neutron diffraction powder pattern obtained at 1.4 K and its magnetic properties were characterized using the data recorded on a SQUID magnetometer and on a magneto-susceptometer. Pb 8 Fe II Fe 2 III F 24 is triclinic, space group P 1 ; its crystal structure was previously solved on a single crystal. The magnetic structure of this fluoride is built up from ferrimagnetic chains antiferromagnetically coupled approximately along the c -axis of the cell, making up layers parallel to the ( b , c ) plane. Two successive layers exhibit different orientations of the magnetic moments. The net magnetic moment of Pb 8 Fe II Fe 2 III F 24 is equal to zero in agreement with an antiferromagnetic structure. This magnetic structure does not evolve in the temperature range: 1.4–20 K. Thus, only one magnetic phase occurs below T T N ≈21 K. Under a sufficiently strong magnetic field ( H >5000 Oe), Pb 8 Fe II Fe 2 III F 24 exhibits a spin-flop transition.