Effect of cation size and disorder on the power loss of La0.7(Ba1−xSrx)0.3MnO3

The power loss PL of La0.7(Ba1-xSrx)0.3MnO3 (0≤x≤1) as a function of temperature, frequency (f) and amplitude of flux density (Bp), has been studied to analyze the effect of A-site cation mean radius and size-disorders σ2. It is found that as f is lower than 1 MHz, PL is proportional to f0.94−1.21Bp2.49−2.97 in the low induction region, and f0.94−1.21Bp2.23−1.53 in the high induction region, indicating that PL is dominated by hysteresis losses. For f approaches 1 MHz, PL of the majority of samples obeys a Bp2.13−2.21 law, which may be attributed to eddy current loss. The temperature dependence of PL displays a peak around the transition from ferromagnetic-metal to paramagnetic-insulator, resembling the feature of the Rayleigh constant η. This case further demonstrates that in the low frequency region, PL predominantly originates from hysteresis loss. A decrease in σ2 with increasing x, will relieve local strain, raising η, thus give rise to an increase in PL.