We show that minimal disturbance to the robust charge-ordered Pr 0.5 Ca 0.5 MnO 3 by 2.5% Al substitution on the Mn site drives the system toward a ferromagnetic ground state. The history-dependent coexisting phases observed are explained as the outcome of a hindered first-order transition with glasslike arrest of kinetics resulting in irreversibility. Consistent with a simple phase diagram having a ferromagnetic ground state, it is experimentally shown that these coexisting phases are far from equilibrium.

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We show that Pr0.5Ca0.5MnO3 with 2.5% Al substitution and La0.5Ca0.5MnO3 (LCMO) exhibit qualitatively similar and visibly anomalous M-H curves at low temperature. Magnetic field causes a broad first-order but irreversible antiferromagnetic (AF)-insulating (I) to ferromagnetic (FM)-metallic (M) transition in both and gives rise to soft FM state. However, the low temperature equilibrium state of Pr0.5Ca0.5Mn0.975Al0.025O3 (PCMAO) is FM-M whereas that of LCMO is AF-I. In both the systems the respective equilibrium phase coexists with the other phase with contrasting order, which is not in equilibrium, and the cooling field can tune the fractions of the coexisting phases. It is shown earlier that the coexisting FM-M phase behaves like 'magnetic glass' in LCMO. Here we show from specially designed measurement protocols that the AF-I phase of PCMAO has all the characteristics of magnetic glassy states. It devitrifies on heating and also recrystallizes to equilibrium FM-M phase after annealing. This glass-like AF-I phase also shows similar intriguing feature observed in FM-M magnetic glassy state of LCMO that when the starting coexisting fraction of glass is larger, successive annealing results in larger fraction of equilibrium phase. This similarity between two manganite systems with contrasting magnetic orders of respective glassy and equilibrium phases points toward a possible universality.