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

Abstract

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±0.02K). 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.