LOW-DIMENSIONAL ELECTRONIC STATES AT METAL SURFACES: QUANTUM WELLS AND QUANTUM WIRES

Abstract

Several possibilities of “engineering” low-dimensional solids on the atomic scale are discussed. The electronic and magnetic structure of such materials is explored for two classes, i.e., multilayers and “wires” attached to step edges. Magnetic multilayers represent a particularly promising case, since quantum effects have macroscopic consequences. Quantization perpendicular to the layers is connected with oscillatory magnetic coupling, which in turn is important for obtaining “giant” magnetoresistance. This effect is being applied towards the fabrication of magnetoresistive reading heads for magnetically stored data. Extensions towards lateral superlattices and quantum wires are explored, where a stepped surface acts as a template. It is found that electrons can be trapped at step edges, and level shifts of the order 0.5 eV are observed for atoms adsorbed at step edges.