Magnetic and dielectric properties of multiferroic Tb_0.5Eu _0.5MnO₃

The structural, magnetic and dielectric properties of multiferroic compound Tb_0.5Eu_0.5MnO₃ are reported near the boundary of the multiferroic phase of the Eu-doped Tb_1-xEu_xMnO ₃ system. The Mn³⁺ moments order in an incommensurate antiferromagnetic manner below T_N 50 K, followed by a spin canting-like response around 25 K. Below T_N, extra hysteresis loops were observed for applied fields B_a around 1-2 T, with decreasing magnetic / K moment for increasing magnetic fields. The dielectric constant ε' showed a peak at 28, which was attributed to the ferroelectric transition in analogy with the parent compound TbMnO₃. Structural analysis indicates the Mn-O2-Mn bond angle within the ab-plane is 145.9° suggesting that there exists a critical angle in the perovskite manganate multiferroic systems.