Microstructure, magnetic, and magnetoimpedance properties of electrodeposited NiFe/Cu and CoNiFe/Cu wire: A study on influence of saccharin additive in plating bath

Magnetic thin films of NiFe and CoNiFe were electrodeposited from three different deposition baths on copper wires of 100 mu m diameter. The magnetic and magneto-impedance (MI) properties of the samples were investigated as a function of saccharin additive concentration in the plating bath. For all intermediate frequencies, the MI ratio increased with saccharin concentration in the plating bath up to a critical concentration and then saturates. The change in MI with saccharin concentration in electrodeposition bath was attributed to the grain size reducing action of saccharin which in turn reduces the coercivity of the film, making it soft magnetic. The origin of MI lies in the combined effect of domain wall motion and spin rotation which contributes to permeability. Inductance spectroscopy was used to evaluate the magnetic characteristic of the samples by modeling magnetic film-coated wires in terms of equivalent electrical circuit; namely parallel inductance and resistance circuit in series with series A circuit. The domain wall motion was found to be greatly affected by saccharin addition to the bath, which was revealed through the study of variations in these circuit parameters. The domain wall motion thereby affects the magnetic softness of samples, which is reflected by MI enhancement. (C) 2011 American Institute of Physics. [doi:10.1063/1.3549149]