Griffiths phase and its evolution with Mn-site disorder in the half-doped manganite Pr0.5Sr0.5Mn1-yGayO3 (y=0.0, 0.025, and 0.05)

We show Griffiths phase (GP)-like behavior in half-doped Pr0.5Sr0.5MnO3 having ferromagnetic (FM) spin correlation above FM transition (T-C) without any spontaneous magnetization. Temperature range and exponent of GP increase with Ga substitution at Mn site which is not related with structural disorder as Ga does not affect the structure, moreover, reduces Jahn-Teller active Mn3+ ions. FM clusters both above and below T-C reduces their size with Ga. Hence, it is considered that GP originates from phase inhomogeneity and evolves with addition of disorder due to change in its length scale.