GMR study leading to sensor fabrication on the Ag–Co system

The Ag–Co system either in multilayer or in granular alloy form exhibits the Giant MagnetoResistance (GMR) effect. By adjusting the modulation parameters an intermediate structure may be formed offering new possibilities for magnetoelectronic applications. This structure resides in the limit between multilayers and granular alloys and is called granular multilayer. This work deals with the Ag–Co system and involves film growth by e-beam evaporation, structural characterisation by X-ray and TEM facilities together with magnetic (SQUID) and magnetotransport measurements. The dependence of GMR values on the individual layer thickness and on the total film thickness was parameterised and magnetoresistance values of 16% at 300 K and 36% at 30 K were achieved. The outcome of this study is the fabrication of a two-dimension magnetic field sensor consisting of eight specific elements forming a 2×4 array. The sensor is specialised in small magnetic field regions while its response was found quite satisfactory regarding its uniformity and repeatability. The sensor may be upgraded to larger arrays and to three dimensions in order to fulfil various market needs.