Optical probing of magnetic inert layers

The thickness of a magnetic inert layer on top of a ferrite head sample was measured by probing the longitudinal Kerr effect as a function of the angle of incidence of a laser beam. Our computerized measuring system used a simple single-detector setup to derive polarization information from a Kerr-reflected beam as the incident angle was scanned. The results were analyzed using a general theory of reflection from magnetic stratified media. The experimental results indicate that the possible inert-layer thickness values are given by (50 +/- 10) + 60 x N nm, where the order N equals 0, 1, 2, 3, or 4.