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The b-axis oriented orthorhombic YMnO3 (o-YMnO3) epitaxial films on a
YAlO3 (010) substrate were fabricated with pulsed-laser deposition. The
anisotropic orbital occupation and Jahn-Teller (JT) distortion of an
o-YMnO3 film were investigated with polarization-dependent x-ray
absorption spectra and configuration-interaction multiplet-cluster
calculations. A significant energy difference, similar to 3.8 eV, for
the main white line along E//b and E//a in polarization-dependent Mn
K-edge spectra of o-YMnO3 indicates an extraordinary JT distortion and
significant anisotropic Mn-O bonding within the ab plane in the o-YMnO3
film. Most importantly, although the orbital occupation of 3d electrons
in o-YMnO3 films is almost the same as that in single crystalline
o-DyMnO3, the JT distortion of o-YMnO3 films is larger than that of
single crystalline o-DyMnO3, deduced from the multiplet calculations. We
speculate that this JT distortion predominantly contributes to the
origin of the cycloidal spin deformation in bulk o-YMnO3, because of a
suppressed nearest-neighbor superexchange interaction and an enhanced
next-nearest-neighbor superexchange interaction. These complementary
results provide insight into the origin of the E-type magnetic
configuration of o-YMnO3. (C) 2014 AIP Publishing LLC.
