Magnetic properties of Ni-Co thick-film magnetoresistors

Magnetic susceptibility from 300 to 900 K, room temperature hysteresis cycl es and saturation magnetization were investigated in screen printed and fir ed NiCo-based layers prepared at various peak temperatures. A bulk NiCo met al sheet of comparable composition was also studied. Values of the magnetic polarization J of 0.28 and 0.435 T were obtained (at 200 kA/m) for films p repared at 750 and 950 degrees C, respectively, in contrast with J = 0.98 T for the bulk alloy. In addition, the magnetoresistive responses of the lay ers and the sheet were plotted. These data suggest that strains, pores and lack of composition homogeneity in the films concur in affecting their magn etic properties, and are responsible for their reduced magnetoresistance an isotropy (e.g. ca. 4% for films as compared to ca. 8% for the bulk alloy at H = 80 kA/m). (C) 1999 Elsevier Science S.A. All rights reserved.