Structural correlation of magneto-electric coupling in polycrystalline TbMnO3 at low temperature

The present study is focused on the structural correlation of magneto-electric coupling that exists in polycrystalline TbMnO 3 . The X-ray diffraction patterns are collected at various conditions, which are (1) at 300 K without a magnetic field, (2) at 2 K without magnetic field and (3) at 2 K with 7 Tesla magnetic fields. The structural transition in TbMnO 3 has been observed at 2 K and some lattice modulation after applying the magnetic field at 2 K. The Rietveld refinement of TbMnO 3 confirms the orthorhombic phase with centrosymmetric space group Pnma at 300 K. We have observed that the inversion symmetry breaks at 2 K and the polycrystalline TbMnO 3 has been refined using a non-centrosymmetric orthorhombic space group which can be either Pn2 1 a or P2 1 ma. This structural transition confirms the presence of a ferroelectric phase at 2 K. After the application of 7 Tesla magnetic field, the signature of an incommensurate phase has been observed in polycrystalline TbMnO 3 at 2 K. The DC magnetization behaviour with temperature M(T) and field M(H) reveals the antiferromagnetic behaviour of polycrystalline TbMnO3 below 42 K. We have also measured magneto-dielectric property of polycrystalline TbMnO 3 at the low temperature, which confirms the strong magneto-electric coupling in polycrystalline TbMnO 3 below the transition temperature.