Materials for spintronics

The spin dependent conduction of ferromagnetic materials in heterostructures gives rise to new phenomena such as giant magnetoresistance (GMR) in magnetic multilayers or tunnel magnetoresistance (TMR) in magnetic tunnel junctions. We review the mechanism of GMR and TMR and experimental results which emphasize the influence of different parameters on these phenomena, taking as an example the case of the widely used transition metals. The integration of ferromagnetic materials and semiconductors is also discussed. The potential of newly emerging materials for spin-electronics or spintronics such as half-metals for fully spin-polarized electrodes, ferromagnetic insulators as spin-dependent tunnel barriers, and ferromagnetic semiconductors is described.