Study of non local optical process in soft x-ray region

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The crystal structure of LuFe2O4 has the alternate staking of triangular lattices of rare-earth elements, iron, and oxygen. The charge ordering of Fe2+ and Fe3+ ions in LuFe2O4 induces ferroelectricity below 330 K (Tco: charge order temperature). Above Tco, the three dimensional charge order changes into the two dimensional. In this study, the temperature dependence and polarization dependence of the X-ray emission spectra (XES) at Fe 2p-edge was investigated in order to study electric states in charge order state and charge disorder state. It was found that, in charge order state, Fe 2p edge -XES showed not only local optical process on each Fe2+ and Fe3+ site but also a non-local optical process between the Fe2+ and Fe3+ sites. It was found that the process was clear in plane direction. And more the non-local aspect was not clear in the charge disordered state.