Field induced changes in cycloidal spin ordering and coincidence between magnetic and electric anomalies in BiFeO3 multiferroic

Abstract The temperature dependences of ZFC and FC magnetization was measured for BiFeO 3 ceramics in magnetic field up to μ 0 H =10 T and in temperatures from the range 2–1000 K. The antiferromagnetic order was detected from the hysteresis loops below the Neel temperature T N =646 K. The anomaly in M ( H ), which occurred in the low magnetic field range, was ascribed to the field-induced transition from circular cycloid to the anharmonic cycloid. At high field limit, we observed the field-induced transition to the homogeneous spin order. From the M ( H ) dependence, we deduced that the spin cycloid becomes anharmonic above the field H a that caused nonlinear magnetization. The cycloid vanished above the field H c and the system again exhibited linear magnetization M ( H ). The anomalies in the electric properties, e ′( T ), tanδ ( T ), and σ ( T ), which are manifested within the 635–670 K range, coincide with the anomaly in the temperature dependence of magnetization M ( T ), which occurs in the vicinity of T N =646 K. We propose that this coincidence can be explained by the critical behavior of chemical potential µ S , related to the magnetic phase transition.