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

Abstract The power loss P L of La 0.7 (Ba 1- x Sr x ) 0.3 MnO 3 (0≤ x ≤1) as a function of temperature, frequency ( f ) and amplitude of flux density ( B p ), has been studied to analyze the effect of A-site cation mean radius r A > and size-disorders σ 2 . It is found that a s f is lower than 1 MHz, P L is proportional to f 0.94 − 1.21 B p 2.49 − 2.97 in the low induction region, and f 0.94 − 1.21 B p 2.23 − 1.53 in the high induction region, indicating that P L is dominated by hysteresis losses. For f approaches 1 MHz, P L of the majority of samples obeys a B p 2.13 − 2.21 law, which may be attributed to eddy current loss. The temperature dependence of P L 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, P L predominantly originates from hysteresis loss. A decrease in σ 2 with increasing x , will relieve local strain, raising η , thus give rise to an increase in P L .