Molecular tilting and columnar stacking of Fe phthalocyanine thin films on Au(111)

Abstract

Scanning tunneling microscopy and x-ray absorption spectroscopic results at the Fe K edge of Fe phthalocyanine (FePc) thin films grown on Au substrates, together with theoretical calculations, allow us to refine the structure of the film. In particular, we show that the columnar stacking of the FePc molecules is different from that found in bulk α and β phases. Moreover, the molecules do not lay parallel to the surface of the substrate. These structural findings are relevant to understand magnetism of FePc films.

Controlling Ferromagnetic Ground States and Solitons in Thin Films and Nanowires Built from Iron Phthalocyanine Chains

“…It can also be seen that the overall magnetization of the templated film is larger than that of the nontemplated film, with the magnetization curve for the templated film appearing to be flatter and therefore closer to saturation in the high‐field region. These differences arise due to magnetic anisotropy, with the moment preferring to lie in the plane of the molecule, as previously observed on sapphire and gold substrates, and depicted in Figure c …”

Influence of substrate on molecular order for self‐assembled adlayers of CoPc and FePc

“…Scanning tunneling microscopy (STM) study for the room temperature deposition of FePc on Au(111) shows that molecules adopt columnar stacking structure on Au(111). The molecules lie on the substrate with small tilt angle at low film thickness due to higher molecule–substrate interactions . It is the strength of molecule–substrate and molecule–molecule interactions that generally control the self‐assembly of the molecules and first layer may direct the orientation of further layers.…”

Quadrupolar XMCD at the FeK-edge in Fe phthalocyanine film on Au: Insight into the magnetic ground state

“…This can be related to the fact that in the state (2), the expectation value O zzz appearing in Carra's sum rule, is proportional to L z . Similarly in the perpendicular direction O ααα is proportional to L α (α = x, y) (see Eq.s (13) and (16) in SM II). At an angle γ, in the conditions of the experiment (saturating magnetic field along the incident photon direction), µ L = µ ⊥ cos 2 γ + µ sin 2 γ [3].…”

“…1c, the angular dependence of the quadrupolar signal at 7112 eV is quite anomalous. First of all, contributions from 3d-4p mixing are excluded, since the stack preserves the inversion symmetry of the isolated molecule [13]. Its intensity is maximum in normal incidence (γ = 0…”

“…(3) one obtains µ ⊥ = 0.60 ± 0.08 µ B and µ = 0.23 ± 0.03 µ B in excellent agreement with the experimental values. This step quantitatively determines the ground state |GS of the FePc molecule in the stack [13], within our approximations.…”