Molecular magnetism in thin metallo-supramolecular films: A combined neutron and soft x-ray reflectometry study

A detailed reflectometry study of Langmuir–Blodgett multilayers composed of a polyelectrolyte-amphiphile complex (PAC) is presented. The PAC is self-assembled from metal ions, ditopic bis-terpyridines and amphiphiles. The structure as well as the vacuum stability of the LB multilayer is investigated by soft x-ray reflectometry. The multilayer has a periodicity of 57 Å, which corresponds to an architecture of flat-lying MEPE rods and upright standing amphiphiles (hexadecyl phosphate, DHP). The films remain stable under high vacuum conditions. X-ray magnetic circular dichroism reveals a magnetic moment of 0.5μB/Fe2+ carried by the iron ions within the films. Using spin-resolved neutron reflectometry, Langmuir–Blodgett-films of PAC are identified as magnetic multilayer systems with the same characteristic dd-spacing as it is found for the structural multilayer periodicity. The separation of the edges of total external reflection for spin up and spin down neutrons in presence of a magnetic moment is studied by time-of-flight neutron reflectometry.