Heat capacity, thermopower and magnetoresistance effects in multiferroic La_0.5Bi_0.5Mn_0.5Fe_0.5O₃

We have carried out systematic investigations in perovskite multiferroic La_0.5Bi_0.5Mn_0.5Fe_0.5O₃ by means of X-ray diffraction, magnetisation, electrical resistivity, thermoelectric and heat capacity measurements. The magnetic behaviour of this composition is rather complex, though the magnetisation curve seems to be like a weak ferromagnetic material. However, there is no clear evidence of λ-anomaly in the heat capacity data down to 2 K, yet this behaviour corroborate the trends of semiconducting silicon below room temperature. The sensitivity of magnetic behaviour to the iron-manganese ratio is also demonstrated. In presence of an external field of 7 T, it exhibits a magnetoresistance of −5 % at 130 K. The thermoelectric value increases linearly with decreasing temperature, and at room temperature the value is +85 μV/K, which is associated with the p-type polaronic conductivity.