Role of Spacer Thickness on Magnetoresistance Characteristics under Mechanical strain

Nowadays the GMR research moved into new areas by combining GMR ferromagnetic layers with materials exhibiting magnetostriction phenomena. If the sense layer of SV (spin valve) is substituted by magnetostrictive material, the magnetoresistance structure is influenced by the applied tensile or compressive stress through the magnetization orientation in magnetostrictive material. Using such effect, the sensor of mechanical quantities can be constructed. For SV applications as a mechanical sensor more flexible substrate is needed. In this paper is studied role of SV spacer thickness on magnetoresistance characteristics under mechanical load. The magnetoresistance was measured in Co-Au-Co core structure with spacer thickness in range of 2.2 - 4 nm deposited on plastic substrate. Magnetoresistance dependency vs. applied strain was measured in bending configuration. Various types of characteristics were observed in dependence of spacer thickness. These properties are studied in connection with oscillatory character of antiferromagnetic exchange coupling forces which was in good correlation with our experimental results.