Magnetic ordering in relaxor ferroelectric (1 − x)Pb(Fe_2/3W_1/3)O₃–xPbTiO₃ single crystals

Single crystals of the perovskite solid solution (1 − x)Pb(Fe_2/3W_1/3)O₃–xPbTiO₃, with x = 0, 0.07, 0.27, and 0.75, have been synthesized by the high-temperature solution growth using PbO as flux and characterized by x-ray diffraction and dielectric and magnetic measurements. The crystal structure at room temperature changes from a pseudocubic to a tetragonal phase with the PbTiO₃ (PT) content increasing to x ⩾ 0.27. As the amount of PT increases, the relaxor ferroelectric behavior of Pb(Fe_2/3W_1/3)O₃ (PFW) is transformed toward a normal ferroelectric state with sharp and nondispersive peaks of dielectric permittivity at T_C. Two types of magnetic orderings are observed on the temperature dependence of the magnetization in the crystals with x ⩽ 0.27. This behavior is explained based on the relationships among the magnetic ordering, perovskite structure, composition, and relaxor ferroelectric properties. Furthermore, the macroscopic magnetization of the system was measured under the application of a magnetic field, which demonstrates different magnetic behavior associated with the weakly ferromagnetic, antiferromagnetic, and paramagnetic ordering in the temperature range of 2 to 390 K. Interestingly, the low-temperature ferromagnetism is enhanced by the addition of ferroelectric PT up to x = 0.27.