摘要
Multiferroic YMn 1-x Fe x O 3 (020) (x = 0.125, 0.25, 0.50) epitaxial thin films with an orthorhombic structure (space group Pbnm) were prepared on a YAlO 3 (010) substrate by pulsed-laser deposition. Upon Fe substitution, the b-axis was clearly shortened, whereas the a- and c-axes were slightly lengthened based on XRD analysis. To understand the influence of orbital polarization and the Jahn-Teller effect of Mn 3+ on Fe substitution and also the local octahedral-site distortion of Fe 3+ in an environment of Jahn-Teller-active Mn 3+ ions in YMn 1-x Fe x O 3 films, we measured the polarization-dependent X-ray absorption spectra at the Mn-L 2,3 and Fe-L 2,3 edges, and also simulated the experimental spectra using configuration-interaction multiplet calculations. Although Δe g for the Mn 3+ ion decreased from 0.9 eV in pure YMnO 3 to 0.6 eV in the half-Fe-substituted sample, a single e g electron was still strongly constrained to the d 3 y 2 -r 2 orbital for all the Fe concentrations tested. The largest Δe g , 0.5 eV, for the Fe 3+ ion was derived for a sample with 12.5% Fe substitution, and gradually decreased to 0.15 eV for the half-Fe-substituted sample. The local octahedral-site distortion of the Fe 3+ ion inside the YMnO 3 lattice was similar to that of the Mn 3+ ion, whereas the Jahn-Teller distortion and GdFeO 3 -type distortion of the Mn 3+ ion were decreased by the spherical high-spin Fe 3+ ions. The combination of the experimental and theoretical data provides both profound insight into the variation of the Jahn-Teller distortion and orbital anisotropy and instructive information about the magnetic structures in these orthorhombic YMn 1-x Fe x O 3 thin films.