LAUSR

Abstract The critical behavior associated with the magnetic phase transition has been investigated by magnetization isotherms in La 0.6 Ca 0.4− x Sr x MnO 3 nano-particle compounds for x  = 0 (S0C1), 0.05 (SC. 4-4) and 0.4 (S1C0). The critical exponents are estimated by various techniques, such as the Modified Arrott plot, Kouvel–Fisher plot and critical isotherm techniques. Thus, the average values of the critical exponent and the critical temperature obtained by the different methods are ( β m o y = 0.47 ; γ m o y = 1.02 ; δ m o y = 3.00 ; T C = 230.6 K ) for S0C1, ( β m o y = 0.47 ; γ m o y = 1.00 ; δ m o y = 3.21 ; T C = 361.9 K ) for S1C0, and ( β m o y = 0.26 ; γ m o y = 1.02 ; δ m o y = 4.92 ; T C = 286.4 K ) for SC. 4-4. These values are in good agreement with those given by the theoretical models: Mean-Field model ( β  = 0.5, γ  = 1 and δ  = 3) for S0C1 and S1C0 compounds; and Tricritical mean-Field model ( β  = 0.25, γ  = 1 and δ  = 5) for SC. 4-4 one. The reliability of the critical exponent values was confirmed by the Widom scaling relation and the universal scaling hypothesis.