Search

The concept of using comparison between magneto-optic measurements taken in the linear and second-harmonic reflected fields to address problems attending the development of ultra-high-density recording media as the limits of thermal stability are approached is presented. It is shown how magneto-optical measurements made routinely in the linear reflected field to access many of the bulk characteristics of such media may, by operating in the second-harmonic field, be fruitfully extended. To illustrate the techniques being explored, reference is made to initial measurements on a longitudinal recording medium under continuing development at Coventry. This medium, already shown to support recording at linear densities in excess of 100 kfci, is based on cobalt particles around 10 nm in diameter. [ABSTRACT FROM AUTHOR]

The behaviour of the reflectivity and Kerr magneto-optic effects in the non-linear second-harmonic (SH) field diffracted from nano-scale structured ferromagnetic interfaces is reported. Measurements are made in both the linear and non-linear fields at two different fundamental wavelengths (1064 nm and 800 nm) and their associated harmonics. Resonant behaviour observed as a function of angle of incidence is identified with surface-plasmon production that is known to intensify the local field within the interface. Radiation incident at angles of incidence that optimise coupling to the electron plasma produces an increase in the SH field radiated in the vicinity of those angles. Similarly, at those angles of incidence where radiation at the SH wavelengths (532 nm and 400 nm) couples optimally to the electron plasma, troughs are seen in the angular spectrum of the generated SH radiation. Kerr magneto-optic measurements taken in both the linear field and the SH field both show very significant enhancement at angles meeting the plasma-resonance condition. The totality of experimental data presented allows the conclusion that intensification of the interface electric field due to plasmon creation enhances not only the SH reflection coefficient, as was already known, but also the magneto-optic reflection coefficients in both linear and SH fields. [ABSTRACT FROM AUTHOR]