Modulation of multiferroic properties of h-YMnO3 due to lattice distortion caused by Yb doping

Because of their unique electrical and magnetic properties, the perovskite multiferroic materials exhibit significant potential in spintronic device applications. However, synthesizing room-temperature multiferroic materials with robust magneto-electric coupling effects remains a major challenge. In this work, Yb³⁺, with an ionic radius slightly smaller than Y³⁺, was selected for A-site doping in the h-YMnO₃, which has a high ferroelectric transition temperature (T_C ~ 900 K) and a low antiferromagnetic transition temperature (T_N ≤ 70 K). This similar ionic radius allows Yb to substitute the Y site effectively while introducing distinct electronic states, thereby optimizing the structure and multiferroic properties of h-YMnO₃ without significantly altering the crystal structure. A series of Yb-doped Y_1-xYb_xMnO₃ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1) materials were synthesized via conventional solid-phase reaction. The effects of Yb doping on the structure, magnetism, and ferroelectricity of h-YMnO₃ were studied. X-ray diffraction (XRD) and corresponding XRD refining results show that as Y³⁺ is replaced by Yb³⁺ with smaller radii, the cell parameters and cell volume of Y_1-xYb_xMnO₃ decrease, the cell is compressed, and the lattice structure of Y_0.5Yb_0.5MnO₃ obtained under the condition of Yb semi-doping changes significantly. Subsequent magnetic and room-temperature ferroelectric test results show that the Y_1-xYb_xMnO₃ series samples have anti-ferromagnetic ground states. In particular, the proper inclination of Mn³⁺ ions in the double perovskite structure of Y_0.5Yb_0.5MnO₃ generates strong Dzyaloshinskii-Moriya (DM) interactions, resulting in relatively strong antiferromagnetism. The antiferromagnetic Neel temperature (T_N) from 37 K to 41 K. Yb³⁺-induced inclined ferroelectricity enables Y_0.8Yb_0.2MnO₃ to achieve the highest ferroelectric polarization of 0.030 µC cm⁻², which is 180% greater than that of h-YMnO₃. The results demonstrate that Yb doping plays a crucial role in regulating the structure and multiferroic properties of h-YMnO₃, offering a novel strategy for developing room-temperature multiferroic materials with robust magneto-electric coupling.