Induced magnetic ordering in a molecular monolayer

Chemically tunable molecular magnets exhibit new and attractive properties, particularly in the field of spintronics. In this work, the magnetic interaction between a magnetized thin film cobalt substrate and adsorbed manganese(III)-tetraphenylporphyrin chloride (MnTPPCl) molecules has been studied by X-ray magnetic circular dichroism (XMCD). For MnTPPCl submonolayer coverages circular dichroism is observed at the Mn LIII,II-edges. From temperature dependent studies and element-specific hysteresis curves, it is concluded that a net magnetization is induced on the complexed Mn in the adsorbed molecule. To our knowledge, this is the first clear evidence that exchange coupling between a large organic adsorbate and a ferromagnetic substrate are observable by XMCD.