论文部分内容阅读
The critical properties of the mixed manganite La0.67–x Y x Ba0.23Ca0.1Mn O3 with x=0.10 and x=0.15 around the paramagnetic(PM)-ferromagnetic(FM) phase transition were investigated through various techniques. These involved modified Arrott plots, Kouvel-Fisher method and Widom scaling relation. Magnetic data, analyzed in the critical region, using the above methods, yielded the critical exponents for(x=0.10) La0.57Y0.10Ba0.23Ca0.1Mn O3(β=0.312±0.002 and γ=1.147±0.003 at T C=299.23±0.05 K). Moreover, the estimated critical exponents of(x=0.15) La0.52Y0.15Ba0.23Ca0.1Mn O3 were β=0.286±0.004 and γ=0.943±0.002 at T C=289.53±0.06 K. The critical exponents’ values were close to the theoretical values of 3D-Ising model and tricritical mean-field model. These results suggested that the present composition should be close to a tricritical point in the La0.67–x Y x Ba0.23Ca0.1Mn O3 phase diagram. Expressing the field dependence as ΔS M∝H n allowed us to establish a relationship between the exponent n and the critical exponents of the material and to propose a phenomenological universal curve for the field dependence of ΔS M.
The critical properties of the mixed manganite La0.67-x Y x Ba0.23Ca0.1Mn O3 with x = 0.10 and x = 0.15 around the paramagnetic (PM) -ferromagnetic (FM) phase transition were investigated through various techniques. These involved modified Arrott plots, Kouvel-Fisher method and Widom scaling relation. Magnetic data, analyzed in the critical region, using the above methods, yielded the critical exponents for (x = 0.10) La0.57Y0.10Ba0.23Ca0.1MnO3 (β = 0.312 ± 0.002 and γ = 1.147 ± 0.003 at TC = 299.23 ± 0.05 K). Moreover, the estimated critical exponents of (x = 0.15) La0.52Y0.15Ba0.23Ca0.1MnO3 were β = 0.286 ± 0.004 and γ = 0.943 ± 0.002 at TC = 289.53 ± 0.06 K. The critical exponents’ values were close to the theoretical values of 3D-Ising model and tricritical mean-field model. These results suggest that the present composition should be close to a tricritical point in the La0. 67-x Y x Ba0.23Ca0.1Mn O3 phase diagram. Expressing the field dependence as ΔS MαH n allowed us to establish a relationship between the exponent n and the critical exponents of the material and to propose a phenomenological universal curve for the field dependence of ΔS M.