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We have investigated the structural and magnetic phase transitions in Sr doped polycrystallineTb0.55Sr0.45MnO3, using temperature-dependent high-resolution neutron powder diffraction in the HRPTdiffractometer at PSI to address the origin of magnetization reversal at low temperature. The solid so-lution Tb0.55Sr0.45MnO3 crystallizes in O' type orthorhombic structure having the Pnma symmetry. Thesubstitution of the divalent cation of Sr2 at the site of Tb3þdilutes the Mn-Tb interaction and affects themagnetic structure, which was observed by thefield and temperature-dependent dc magnetization and neutron diffraction study. The temperature-dependent zero field-cooled and field cooled dc magnetization study reveals the indication of spin reversal phenomena, which is the nature of canted antiferromagnetic or ferrimagnetic transition at 100 Oe because of Mn-Mn sub-lattices interaction below 65 K. By increasing the applied magneticfield up to 20 kOe, a weak ferromagnetic type of behaviour isobserved. The field-dependent magnetization shows weak coercivity due to the canted spin structure atlow temperatures. The low-temperature neutron diffraction study of polycrystalline Tb0.55Sr0.45MnO3 reveals the non-collinear canted antiferromagnetic structure due to Tb ordering at 1.5 K, which turns intoa non-collinear ferromagnetic structure along with spin canting followed by the spin reversal phenomena at 25 K.
magnetic study; manganite; neutron diffraction; spin reversal