Measurement of the magnetooptical constants of reactive metals

A method is described for measuring the dielectric tensor of perpendicularly magnetized metal films that are overcoated with a protective transparent layer. It uses a combination of ellipsometric and polar Kerr measurements and employs a series of consistency checks to ensure the accuracy of the data analysis. As an example, the technique is applied to an amorphous terbium-iron alloy that was overcoated in situ with silicon dioxide.