Study of magnetic properties of Ni -Fe -P and Ni -Fe -P-B chemical films

The magnetic properties of as-plated and heat-treated Ni - Fe -P and Ni -Fe -P-B films were investigated as a basis for developing new functional thin films. The amorphous Ni -Fe -P and Ni -Fe -P-B and crystalline Ni -Fe -P-B films were prepared by simply controlling the NaH2PO2 concentration in the bath. The structure of all Ni -Fe -P films, prepared in an NaH2PO2 concentration range of 18- 48 g/l, was amorphous, while the NaH2PO2 concentration for the formation of amorphous Ni -Fe -P-B films ranged from 23 to 38 g/l. The increase of the Fe content is thought to be the reason for the increase in the atomic magnetic moment, and thus results in an increase in the saturation magnetization (Ms). The amorphous Ni -Fe -P films possess superior coercivity (Hc). Similar behavior can also be seen in the case of Ni -Fe -P-B films. The lower squarenesses of as-plated films, compared with those of annealed films, implies that the as-deposited films are inhomogenous. As the films were heated up to 400 degrees C, the homogeneity was obviously improved, and Ms decreased and Hc increased continuously for all the alloy films.