Local spin ordering in the antiferromagnetic as well as paramagnetic LaMnO3 phase revealed by polarized spin-selected 1s→3d absorption spectra

Spin-selected x-ray absorption near edge structures have been studied on single crystal LaMnO3 at 45 K (A-type antiferromagnetic phase) and at 273 K (paramagnetic phase) with polarized x rays. Observed polarization characters have been interpreted in terms of hybridization of Mn 4p orbitals with 3d orbitals of adjacent Mn ions combined with spin-invariance upon transitions. Almost no temperature dependence was observed in the spectra of both polarization, indicating that short-range spin order exists even at a temperature much higher than T-N. An apparent contradiction of the result with bulk magnetic properties can be resolved by assuming that the x-ray absorption process, being so fast, is sensitive to temporal local structures in the vicinity of the central absorbing Mn ion.