Critical end point of the first-order ferromagnetic transition in a Sm_(0.55)(Sr_(0.5)Ca_(0.5))_(0.45)MnO_3 single crystal

摘要

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_(0.5)Ca_(0.5))_(0.45)MnO_3 single crystal. At ambient condition, the system exhibits a first-order FM transition at T_c ≈ 82 K (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 H_(cr) ≈ 11.5 T. 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-x)Sr_xMnO_3 (x≈0.45).