Emergence of Collinear Magnetic Structure in Tb-doped BiFeO3

The search for ways to realize the multiferroic potential of BiFeO3-based compounds is being relevant for three decades. The major problem is a magnetic spatial spin-modulated structure (SSMS) that nullifies the net magnetic moment over the sample volume. In this paper, we research the effect of bismuth ferrite doping with magnetic Tb3+ ions. With the help of zero-field nuclear magnetic resonance (ZF NMR) spectroscopy, we reveal a change in the type of anisotropy from "easy-axis " to "easy-plane " even at 1.5 % terbium doping. Moreover, at 8.5 % Tb doping, the magnetic structure becomes collinear, SSMS deteriorates, while the crystal structure remains rhombohedral. We also observe an additional high-frequency line, similar to the lines found in the La-and Sr-doped BFO spectra, at a frequency of 75.85 MHz. Such a combination of characteristics gives this composition every chance of being a promising multiferroic compound.