Evolution from sinusoidal to collinear A-type antiferromagnetic spin-ordered magnetic phase transition in Tb_1−x Pr _x MnO₃ solid solution

Abstract The present study reports on the structural and magnetic phase transitions in Pr-doped polycrystalline Tb0.6Pr0.4MnO3, using high-resolution neutron powder diffraction (NPD) collected at SINQ spallation source, to emphasize the suppression of the sinusoidal magnetic structure of pure TbMnO3 and the evolution to a collinear A-type antiferromagnetic ordering. The phase purity, Jahn–Teller distortion, and one-electron bandwidth for eg orbital of Mn3+ cation have been calculated for polycrystalline Tb0.6Pr0.4MnO3, in comparison to the parent materials TbMnO3 and PrMnO3, through the Rietveld refinement study from x-ray diffraction data at room temperature, which reveals the GdFeO3 type orthorhombic structure of Tb0.6Pr0.4MnO3 having Pnma space group symmetry. The temperature-dependent zero field-cooled and field-cooled dc magnetization study at low temperature down to 5 K reveals a variation in the magnetic phase transition due to the effect of Pr3+ substitution at the Tb3+ site, which gives the signature of the antiferromagnetic nature of the sample, with a weak ferromagnetic component at low temperature-induced by an external magnetic field. The field-dependent magnetization study at low temperatures gives the weak coercivity having the order of 2 kOe, which is expected due to the canted-spin arrangement or ferromagnetic nature of Terbium ordering. The NPD data for Tb0.6Pr0.4MnO3 confirms that the nuclear structure of the synthesized sample maintains its orthorhombic symmetry down to 1.5 K. Also, the magnetic structures have been solved at 50 K, 25 K, and 1.5 K through the NPD study, which shows an A-type antiferromagnetic spin arrangement having the magnetic space group Pn′ma′.