THEORY FOR SPIN-POLARIZED OSCILLATIONS IN NONLINEAR OPTICS DUE TO QUANTUM-WELL STATES

Using an electronic tight-binding theory we calculate the nonlinear ma gneto-optical response from an x-Cu/Fe/Cu(001) film as a function of f requency and Cu overlayer thickness (x = 3-25). We find very strong sp in-polarized oscillations with periods of 6 and 11 monolayers due to q uantum well states. These oscillations are enhanced by the large densi ty of Fe d states close to the Fermi level acting as intermediate stat es for frequency doubling. The results show that optical second harmon ic generation is a very sensitive probe of electronic structures and i s even k sensitive.