Dynamic in situ optical and magneto-optical monitoring of the growth of Co/Au multilayers

In situ ellipsometry and Kerr polarimetry have been used to follow, continuously, the evolution of the optical and magneto-optical properties of multiple layers of Co (5 Å) and Au (37.5 Å) during their deposition. A particular feature of the results shows marked oscillations of the magneto-optic polar Kerr effect, with a period of about 16 Å, during the deposition of each Au layer. The appearance of oscillations occurs in both Kerr ellipticity and rotation in a way that depends upon underlying buffer layer thickness and the number of bilayer periods in the multilayer stack. Magneto-optical oscillations have been reported previously in Co/Au and Fe/Au systems and have been interpreted as being a consequence of magneto-optic transitions associated with quantum-well states in the noble-metal layer. The comprehensive optical and magneto-optical measurements reported here allow intrinsic material properties to be determined for developing ultrathin layers. These facilitate a better understanding of the observed magneto-optical signals that result from such structures and also provide a means of predicting such signals for any optical system.