Magnetic, electrical transport and electron spin resonance studies of Fe-doped manganite LaMn0.7Fe0.3O3+δ

We have investigated the magnetic, electrical transport and electron spin resonance (ESR) properties of polycrystalline Fe-doped manganite LaMn0.7Fe0.3O3+δ prepared by sol–gel method. A typical cluster-glass feature is presented by DC magnetization and AC susceptibility measurements and a sharp but shallow memory effect was observed. Symmetrical Lorentzian lines of the Mn/Fe spectra were detected above 120K, where the sample is a paramagnetic (PM) insulator. When the temperature decreases from 120K, magnetic clusters contributed from ferromagnetic (FM) interaction between Mn3+ and Mn3+/Fe3+ ions develop and coexist with PM phase. At lower temperature, these FM clusters compete with antiferromagnetic (AFM) ones between Fe3+ ions, which are associated with a distinct field-cooled (FC) effect in characteristic of cluster-glass state.