The influence of dielectric layers on the magnetic properties of thin GdFeCo layers for in-plane MAMMOS/MSR media

Abstract The effect of adjacent dielectric layers on sputter deposited GdFeCo, of thickness 10–30 nm, suitable as the readout layer for in-plane magnetic amplifying magneto-optic systems, was investigated by measuring the magnetic hysteresis using magneto-optical Kerr effect at room temperature and above. It was found that the magnetic properties were sensitive to the GdFeCo thickness and the presence of the dielectric layer material. Although alternative materials, ZnS and SiN, were also considered, the paper concentrates on the effects of reactively sputtered AlN, which was the only dielectric that produced the required properties for such thin GdFeCo layers of this type. The effect of reducing GdFeCo thickness was similar to that of reducing Gd content. The percentage of nitrogen used in the sputtering gas during AlN deposition was seen to be crucial to the magnetic properties and to the stability of the films. Films 10 nm thick were particularly affected, the best results requiring less nitrogen than was needed for the thicker films.