Magnetoimpedance effect in NiFeP thin films deposited on Cu microwire through electrodeposition

Abstract

Thin coatings of the Nickel–Iron–Phosphorous (NiFeP) alloy is electrodeposited onto copper microwire while varying phosphorus ion concentration in the bath. With increasing phosphorus ion concentration in the deposition bath up to 1 mM, reduced surface roughness, crystallite size and coercivity is witnessed which reflects in enhanced magnetoimpedance (MI) ratio of the plated wires. Maximum MI ratio of 378% and sensitivity of 25 %/Oe is observed at 100 kHz driving frequency for film deposited using 1 mM of P ion in the electrodeposition bath. This enhancement is associated with the reduction of crystallite size and magnetocrystalline anisotropy due to leading formation of amorphous deposits with the optimized incorporation of P atoms coupled with reduction of surface roughness. Additionally, the experimental results of MI measurements are compared with a analytical model and the model parameters related to the circumferential permeability of the NiFeP magnetic film is extracted from it. These parameters are further used to calculate the circumferential permeability of the samples, which is then mapped to a color-coded visualization of current density variation across the wire cross-section, providing a detailed insight into the impedance change.