Highly unquenched orbital moment in textured Fe-phthalocyanine thin films

X-ray magnetic circular dichroism (XMCD) measured at T=6 K and μ₀H=5 T on the α-phase Fe-phthalocyanine (FePc) textured thin films shows that the Fe²⁺ ions present an unusually large, highly unquenched mL=0.53±0.04 μB orbital component, with planar anisotropy. The spin mS=0.64±0.05 μB and the intra-atomic magnetic dipolar mT components were also obtained. The mL/mS=0.83 ratio is the largest measured in $3d$ complexes and compounds. The origin of this unusually high orbital moment is the incompletely filled eg level lying close to the Fermi energy. This explains the unusually large and positive hyperfine field detected by M\"ossbauer spectroscopy in FePc. The FePc film strong planar anisotropy inferred from XMCD experiments is fully confirmed by magnetization measurements.