Magnetoimpedance in electrodeposited NiFe/Cu composite wires: A study on role of in-situ stress

Microstructure, magnetic and magnetoimpedance properties of Ni80Fe20 (Permalloy) films electrodeposited onto a 100 mu m copper wire under varying stress have been investigated. It is found that the magnetoimpedance and field sensitivity values decreased by -50% and 70% on application of maximum stress 24.9 MPa. Present analysis shows that the crystallite size increases with stress, which in turn controls permeability and MI. The skin depth also seem to depend on microstructural changes which also affects the MI significantly. Comparison of our experimental data to the results obtained from numerical simulations based on Maxwell's and Landau-Lifshitz equations show good agreement. The magnetic measurements are supported by the relative permeability values extracted from the MI data. Present results suggest that MI parameters, such as field sensitivity, MI% and f(max) can also be tuned by applying the stress on the sample during preparation.