Magnetic enhancement across a ferroelectric-antiferroelectric phase boundary in Bi _1-xNd _xFeO ₃

The structural and magnetic properties of well-prepared Bi _1-xNd _xFeO ₃ (0 ≤ x ≤ 0.2) powders are investigated by combining x-ray diffraction, Raman scattering spectra, and magnetic measurements. Structural symmetric breaking from rhombohedral R3c to orthorhombic Pnma at the substituted Nd concentration of x = 0.125-0.15, accompanying a ferroelectric-antiferroelectric phase transition, is identified from x-ray diffraction patterns and Raman scattering spectra. The magnetization enhancement of Bi _1-xNd _xFeO ₃ is observed before approaching ferroelectric-antiferroelectric phase boundary conditions (0 ≤ x ≤ 0.15). We consider that such enhancement results from the destruction of the spin cycloid accompanying the structural transition. At x ≥ 0.15, the magnetization decreases, which is probably attributable to further degradation of the space modulated spin structure, allowing a more perfect antiferromagnetic ordering.