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Free keywords:
iron compounds; thin films; surface potential; scanning tunnelling microscopy; field emission; moire fringes
Abstract:
We have studied a thin FeO film on Pt(111) using scanning tunneling microscopy. The corrugation of the Moiré pattern, that arises due to a lattice mismatch between the oxide film and the substrate, is found to increase dramatically when the microscope is operated in the field-emission regime. This contrast enhancement can be attributed to variations in the energy at which field-emission resonances are observed. We assign this effect to variations of the surface potential within the Moiré unit cell. Using a simple electrostatic model we show that in this oxide film with polar termination, such variations can be induced by very subtle differences in geometry.
