Magnetic and Mössbauer studies of 5% Fe-doped BiMnO 3

Abstract

57Fe Mössbauer spectroscopy, dc and ac magnetization, specific heat, and differential scanning calorimetry measurements were performed in a powder BiMn 0.95Fe 0.05O 3 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 BiMn 0.95Fe 0.05O 3 compared with BiMnO 3. On the other hand, the temperature of the monoclinic-to-monoclinic phase transition associated with the orbital ordering strongly decreases in BiMn 0.95Fe 0.05O 3 (414 K) compared with that of BiMnO 3 (474 K). The saturated magnetic moment at 5 K and 5 T is also suppressed from 3.92 μ B per formula unit in BiMnO 3 to 3.35 μ B in BiMn 0.95Fe 0.05O 3. The large quadrupole splitting (1.18 mm/s) observed at 293 K in BiMn 0.95Fe 0.05O 3 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.