Critical end point of the first-order ferromagnetic transition in a Sm_0.55(Sr_0.5Ca_0.5)_0.45MnO₃ single crystal

Abstract

We report on the magnetic field (H ) and hydrostatic pressure (P ) dependence of the order of the ferromagnetic (FM) to paramagnetic phase transition in a Sm_0.55(Sr_0.5Ca_0.5)_0.45MnO₃ single crystal. At ambient condition, the system exhibits a first-order FM transition at TC≈82K (in heating cycle) with strong thermal hysteresis (~13 K). The application of external H and P increases T C, suppresses the hysteresis width, and thus weakens the first-order nature of the transition. Our analysis reveals that the hysteresis vanishes and the first-order FM transition becomes a crossover above a critical magnetic field Hcr≈11.5T. The value of H cr is highest among the manganite family, although the first-order nature of the FM transition is believed to be strongest in Eu_1−xSr_xMnO₃(x≈0.45).