Magnetic and Mössbauer studies of 5% Fe-doped BiMnO3

57Fe Mössbauer spectroscopy, dc and ac magnetization, specific heat, and differential scanning calorimetry measurements were performed in a powder BiMn0.95Fe0.05O3 sample prepared at 6 GPa and 1383 K. The substitution of 5% Fe for Mn increases the temperatures of the structural monoclinic-to-orthorhombic phase transition (from 768 to 779 K) and the ferromagnetic transition (from 98 to 109 K) by about 10 K in BiMn0.95Fe0.05O3 compared with BiMnO3. On the other hand, the temperature of the monoclinic-to-monoclinic phase transition associated with the orbital ordering strongly decreases in BiMn0.95Fe0.05O3 (414 K) compared with that of BiMnO3 (474 K). The saturated magnetic moment at 5 K and 5 T is also suppressed from 3.92 μB per formula unit in BiMnO3 to 3.35 μB in BiMn0.95Fe0.05O3. The large quadrupole splitting (1.18 mm/s) observed at 293 K in BiMn0.95Fe0.05O3 can be explained by the strong Jahn-Teller distortion and cooperative orbital order. The quadrupole splitting reduces by two times above the orbital melting temperature.

Mössbauer spectra of BiMn0.95Fe0.05O3 at 523 and 293 K.Figure optionsDownload as PowerPoint slide