Evolution from sinusoidal to collinear A-type antiferromagnetic spin-ordered magnetic phase transition in Tb_1−xPr_xMnO₃ solid solution

The present study reports on the structural and magnetic phase transitions in Pr-doped polycrystalline Tb_0.6Pr_0.4MnO₃, 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 e_g orbital of Mn³⁺ cation have been calculated for polycrystalline Tb_0.6Pr_0.4MnO_3, 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 Tb_0.6Pr_0.4MnO₃ 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 Tb_0.6Pr_0.4MnO₃ 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′. (paper)