Electronic structure and magnetism of surfaces, interfaces and modulated structures (superlattices)

Recent developments in the study of surfaces and interfaces of metals and of artificial materials such as bimetallic sandwiches and modulated structures are described. Key questions include the effects on magnetism of reduced dimensionality and the possibility of magnetically "dead" layers. These developments have stimulated an intensified theoretical effort to investigate and describe the electronic and magnetic structure of surfaces and interfaces. One notable success has been the development of a highly accurate full-potential all-electron method (the FLAPW method) for solving the local spin density equations self-consistently for a single slab geometry. We describe here this advanced state of ab initio calculations in determining the magnetic properties of transition metal surfaces such as those of the ferromagnetic metals Ni(001) and Fe(001) and the Ni/Cu(001) interface. For both clean Fe and Ni(001) we find an enhancement of the magnetic moments in the surface layer. The magnetism of surface and interface Ni layers on Cu(001) (no "dead" layers are found) is described and compared to the clean Ni(001) results. Finally, the role of μSR experiments in answering some of the questions raised in these studies will be discussed.