Stress in sputtered Co₉₀Fe₁₀/Ag GMR multilayers

Stress, giant magnetoresistance (GMR), structure, and magnetic properties of sputtered (Co₉₀Fe₁₀X angstrom/Ag Y angstrom)×20 multilayer films have been investigated at room temperature where X ranges from 7.5 to 25 angstrom and Y from 10 to 60 angstrom. These films exhibit distinct GMR behaviors dependent on individual layer thicknesses, including layered granular-type GMR in CoFe 7.5 angstrom samples and 'discontinuous' GMR (DGMR) in CoFe 15 and 25 angstrom samples with Ag thicknesses over 30 angstrom. No antiferromagnetic coupling was observed. CoFe 10 angstrom samples act as a transition between GMR behaviors. Compressive stress decreases with increasing Ag thickness in the CoFe 7.5 angstrom samples. In the CoFe 15 and 25 angstrom samples the stress fluctuates similarly depending on Ag thickness. The difference in stress and MR behavior between the CoFe 7.5 angstrom and the 15 and 25 angstrom samples is thought to be due to incomplete CoFe layering in the CoFe 7.5 angstrom samples. In the CoFe 15 angstrom DGMR samples, high temperature annealing resulted in tensile stresses large enough to cause film detachment. X-ray diffraction reveals a strong (111) growth texture as well as satellite peaks from coherent layering. This (111) texture is also evidenced by patterns with hexagonal symmetry formed by the detached films.