Changes in magnetic and magnetoresistive properties of NiFe/Ag multilayers induced by thermal anneal

Permalloy/silver (NiFe/Ag) multilayers, consisting of ten ∼ 5.0 nm and ∼ 2.5 nm thick layers, respectively, were annealed in the 553-693 K interval. Magnetization, resistivity and magnetoresistance of the annealed samples were measured to test their relationship with the structural changes occurring in the multilayer. The results support the previously reported conclusions, namely that during low temperature annealing (up to 633 K) Ag diffusion occurs along the boundaries of the columnar grains, resulting in formation of individual NiFe grains within former permalloy layers. At higher temperature annealing relatively large Ag and NiFe agglomerates grow and break up the multilayered structure. It was shown, that at room temperature the coercive field and magnetoresistance are the most structural sensitive, while the changes in resistivity are masked by phonon scattering contribution.