Cooperative effects generate new electronic and magnetic properties in closed packed organized organic self-assembled monolayers. For many thiolated molecules self-assembled on gold, a surprisingly large magnetic signal was observed (1-5). This new type of "interface magnetism" is not yet theoretically explained. In an attempt to probe another aspect of this new effect, PbS nanoparticles with diameters of 4.2 and 8.2 nm were attached to a p-type of GaAs surface through a self-assembled monolayer of 1,8-octanedithiol. The nanoparticles distribution on the surface was characterized by Atomic Force Microscopy. Field dependent magnetization measurements performed at 5 and 300 K show a paramagnetic signal in the low field region. The magnetic susceptibility of the samples is temperature dependent. The paramagnetic behavior of the samples is explained in terms of charge transfer through the organic monolayer and orbital magnetism.
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