15:00 〜 15:15
▲ [19p-H113-7] Magnetism and x-ray absorption spectra calculations of iron porphyrin
キーワード：metal-organic molecules,x-ray magnetic circular dichroism,magnetic anisotropy
Transition metal porphyrins have attracted attention for possible single molecular magnetic applications because of their complex magnetic ground states and large magnetic anisotropies. Recently the angular dependent x-ray absorption and x-ray magnetic circular dichroism (XMCD) have been measured for iron porphyrin molecules adsorbed on a Cu substrate. First principles calculations are not fully conclusive as for the ground state electronic configuration and cannot explain the angular dependence of the XMCD. Here we report crystal field multiplet calculations of the spectra. We show that the ground state of iron porphyrin has mainly intermediate spin (S=1) and (xy)2 (3z2-r2)2 (xz)1 (yz)1 orbital character. Spin-orbit coupling leads to a singlet ground state with quenched spin- and orbital moment and a large anisotropy of the magnetic susceptibility, which explains the angular dependence of the XMCD measurements. The effect of metal-ligand hybridization on the magnetism is also examined