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.