Bonding anisotropy in multiferroic TbMnO(3) probed by polarization dependent x-ray absorption spectroscopy

Abstract

O K- and Mn L(2,3)-edges x-ray absorption spectra of orthorhombic TbMnO(3) single crystals show strong polarization dependence, in contrast with results of previous experiments on orthorhombic LaMnO(3) and DyMnO(3) thin films that show nearly isotropic spectral structure. First-principles calculations reveal that TbMnO(3) exhibits a zigzag e(g) orbital ordering ground state. The highly distorted MnO(6) octahedron and orbital ordering in TbMnO(3) produce highly anisotropic Mn-O bonding within the ab plane, a frustration of the magnetic ordering, and the formation of complicated incommensurate magnetic structures.