Giant Spin-splitting in the Bi/Ag(111) Surface Alloy

Surface alloying is shown to produce electronic states with a very large spin-splitting. We discuss the long range ordered bismuth/silver(111) surface alloy where an e nergy bands separation of up to one eV is achieved. Such strong spin-splitting enables angular resolved photo emission spectroscopy to directly observe the region close to the band edge, where the density of states shows quas i-one dimensional behavior. The associated singularity in the local density of states has been measured by low temperature scanning tunneling spectroscopy. The implications of this new class of materials for potentia l spintronics applications as well as fundamental issues are discussed.