Cross-type orbital ordering in the layered hybrid organic-inorganic compound (C6H5CH2CH2NH3)2CuCl4

We have studied the magnetic properties and the underlying type of orbital ordering in the layered hybrid organic-inorganic compound $({\mathrm{C}}₆{\mathrm{H}}₅{\mathrm{CH}}₂{\mathrm{CH}}₂{\mathrm{NH}}₃){}₂{\mathrm{CuCl}}₄$ by using ac-magnetic susceptibility and polarization-dependent soft-x-ray absorption spectroscopy at the Cu-${L}₂$ and Cu-${L}₃$ edges. We have established that the compound has a long-range ferromagnetic ordering both in plane and out of plane and we found from the analysis of the absorption spectra that the orbital ordering of the ${\mathrm{Cu}}²⁺$ holes involves the cross-type ${d}_{{x}²\ensuremath{-}{z}²}/{d}_{{y}²\ensuremath{-}{z}²}$ arrangement which is different from the ${d}_{{x}²\ensuremath{-}{y}²}$ arrangement found in the parent compounds of the high-${T}_c$ cuprate superconductors.