Re-entrant spin glass and stepped magnetization in mixed-valence SrFe3(PO4)3

The 2 D channel mixed-valent iron (II/III) monophosphate SrFe3(PO4)3 was synthesized via one step mild hydrothermal method at 210 °C and characterized by X-ray diffraction techniques and magnetization measurements. Coexistence of antiferromagnetic superexchange and ferromagnetic superexchange interactions was supposed to be in the lattice according to the Goodenough–Kanamori–Anderson rules. Temperature dependent DC magnetization measurement shows that SrFe3(PO4)3 is ferrimagnet with three magnetic transitions between 2 and 350 K. Through AC magnetization measurement, re-entrant spin glass was observed due to the competition between ferromagnetic and antiferromagnetic interactions. Furthermore, an interesting field induced stepped magnetization was observed in SrFe3(PO4)3 at 2 K with the saturation magnetization Ms=2.4 μB/f.u. at 5 T.