QUANTUM-WELL STATES AS MEDIATORS OF MAGNETIC COUPLING IN SUPERLATTICES

Quantum well states are found at the Fermi level in Cu on Co(100) and Ag on Fe(100) using inverse photoemission. They appear every 5.9 +/- 0.5 layers in Cu/Co(100), which agrees with the 5.5- to 6-layer oscillation period of the magnetic coupling in Cu/Co(100) superlattices. For Ag/Fe(100) they connect with minority-spin interface states observed below E(F) previously, providing a magnetic coupling channel through the noble metal. These properties are explained in terms of the bulk band structure.