Field-induced first-order to second-order magnetic phase transition in Sm0.52Sr0.48MnO3

We report on the magnetic field (H) dependence of the order of the ferromagnetic (FM) to paramagnetic (PM) phase transition in Sm0.52Sr0.48MnO3 single crystal. For H < 4 T, magnetization and specific-heat data show a first-order phase transition, with sharp drop of magnetization along with hysteresis, and large, symmetric, and narrow specific-heat peak with finite amount of entropy change at T-C. By contrast, for H >= 4 T, the phase transition becomes essentially second-order with tricritical point exponents beta similar to 0.32 and gamma similar to 1.31. The tricritical point separates first-order (H < 4 T) from second-order (H >= 4 T) transition.