Critical parameters near the ferromagnetic-paramagnetic phase transition in La0.5Ca0.5−xAgxMnO3 compounds (0.1≤x≤0.2)

The critical properties of mixed manganite La0.5Ca0.5−xAgxMnO3 (x=0.1 and 0.2) around the paramagnetic-ferromagnetic phase transition are investigated through various techniques such as the modified Arrott plot, Kouvel-Fisher method, and critical isotherm analysis. The magnetic data analyzed in the critical region using the above methods yield the critical exponents for (x=0.1) La0.5Ca0.4Ag0.1MnO3 (β=0.311±0.003 and γ=1.146±0.006 at TC=226.27±0.02 K). Moreover, the estimated critical exponents of (x=0.2) La0.5Ca0.3Ag0.2MnO3 are (β=0.288±0.002 and γ=0.948±0.008 at TC=262.31±0.06). The values deduced for the critical exponents are close to the theoretical prediction of 3D-Ising model and tri-critical mean-field model. These results suggest that the present composition should be close to a tri-critical point in the La0.5Ca0.5−xAgxMnO3 phase diagram.