NONLINEAR MAGNETOOPTICAL KERR-EFFECT STUDY OF QUANTUM-WELL STATES IN A AU OVERLAYER ON A CO(0001) THIN-FILM

We have measured the polar nonlinear magneto-optical Kerr rotation and the total generated second harmonic intensity from a perpendicularly magnetized Co(0001)/Au(111) thin film (6 ML) versus the thickness of a Au overlayer. For both experiments we find a clear oscillation with a period of about 13.5 ML. This behavior can be interpreted as arising from quantum-well. states (QWSs) in the Au overlayer, though interesti ngly, the observed period is twice the expected one. Especially for th e reflected intensity this oscillation is very pronounced: the intensi ty changes by a factor of 10 when the Au overlayer thickness changes f rom 7 to 13 ML. These strong effects make this nonlinear technique ver y suitable for the study of these QW oscillations. (C) 1996 American I nstitute of Physics.