Magntetoelectric (ME) multiferroics, which exhibit coexisting magnetism and ferroelectricity with cross coupling, are being extensively investigated because of the scientific importance of the electronic origin of magnetoelectrics and relevant prospective applications in devices, such as the magnetic-field controlled electro-optic or piezoelectric devices, with new functionalities. The multiferroicity is observed in such manganites as RMnO₃ (R = Dy, Tb, Gd) and TbMn₂O₅. In order to design the devices for the potential applications of RMnO₃ manganites, it is essential to prepare the thin films with a well-defined crystalline structure. In this study, we report the fabrication of the single crystalline orthorhombic DyMnO₃ thin films on different substrates. We investigated the substrate-dependent electronic structure and anisotropic bonding of the Mn 3d states in DyMnO₃ thin films on SrTiO₃(001) and LaAlO₃(110) substrates using polarization-dependent x-ray absorption spectroscopy (XAS) at O K-, Mn L- and Mn K-edges for three polarizations, E || a, E || b and E || c. Polarization-dependent x-ray absorption spectra at O K-, Mn L₂₃- and Mn K-edges of orthorhombic DyMnO₃/LaAlO₃(110) thin films show strong polarization dependence for three polarizations, E || a, E || b and E || c, whereas orthorhombic DyMnO₃/SrTiO₃(001) thin films show nearly isotropic spectral structure. The main peak in polarized Mn L_2,3-edge XAS spectra of DyMnO₃/LaAlO₃(110) thin films for the E || b polarization lies at a lower energy than for polarizations E || a and E || c. The disparate spectra for polarizations E || a and E || b indicate a great anisotropy in Mn 3d-O 2p hybridization and charge transfer from O 2p to Mn 3d, reflecting an orbital ordering and a highly anisotropic coplanar Mn-O bonding in DyMnO₃/LaAlO₃(110) thin films. These results indicate orbital ordering of e_g-orbital and thus the highly anisotropic in-plane Mn-O bonding which is an indispensable factor to the formation of complicated incommensurate modulated magnetic structures observed in orthorhombic DyMnO₃. Utilizing the technique of epitaxial strain stabilization, one can control electronic structure via growing RMnO₃ thin films of the same compound on different substrates. The present results provide important implications for the microscopic understanding of the RMnO₃ manganites.

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