Spin-reorientation magnetic transitions in Mn-doped SmFeO₃

Spin reorientation is a magnetic phase transition in which rotation of the magnetization vector with respect to the crystallographic axes occurs upon a change in the temperature or magnetic field. For example, SmFeO₃ shows a magnetization rotation from the c axis above 480 K to the a axis below 450 K, known as the Γ₄ → Γ₂ transition. This work reports the successful synthesis of the new single-crystal perovskite SmFe_0.75Mn_0.25O₃ and finds interesting spin reorientations above and below room temperature. In addition to the spin reorientation of the Γ₄ → Γ₂ magnetic phase transition observed at around T_SR2 = 382 K, a new spin reorientation, Γ₂ → Γ₁, was seen at around T_SR1 = 212 K due to Mn doping, which could not be observed in the parent rare earth perovskite compound. This unexpected spin configuration has complete antiferromagnetic order without any canting-induced weak ferromagnetic moment, resulting in zero magnetization in the low-temperature regime. M-T and M-H measurements have been made to study the temperature and magnetic-field dependence of the observed spin reorientation transitions.