Long-range ferromagnetic order in perovskite manganite La0.67Ba0.25Ca0.08Mn(1-x)TixO3(x=0.00, 0.05 and 0.10)

摘要

In this study, we report the effects of Ti on the critical behavior of La(0.67)Ba(0.25)Ca(0.08)MnO(3)samples prepared by the flux method. Moreover, the critical exponents beta,gamma and delta are estimated through numerous techniques such as the modified Arrott plot, the Kouvel-Fisher method and critical isotherm analysis of the magnetic measurements on record near the Curie temperature. Compared to standard models, the estimated critical exponents are close to the theoretical values of the mean-field model for these samples. In order to estimate the spontaneous magnetization at a given temperature, we used a process based on the analysis, in the mean-field theory, of the magnetic entropy change (-Delta S-M)vs.magnetization (M). An excellent agreement was found between the spontaneous magnetization determined from -Delta S(M)vs. M(2)and the classical extrapolation from the Arrott curves (mu H-0/M vs. M-2), thus confirming that -Delta S(M)is a valid approach to estimate the spontaneous magnetization in this system. The accuracy of the critical exponent values was confirmed with the scaling hypothesis. The magnetization curves fall onto one of two sides, below and aboveT(C).