Characteristics of Highly Sensitive Magnetoresistive Sensors

A barber-pole type magnetoresistive sensor with excellent sensitivity and temperature characteristics is described. 76 wt% Ni-Fe layers 480 Å and 1030 Å thick were vapor deposited with a TaMo adhesive layer and Au patterning; magnetic field annealing was used to induce uniaxial anisotropy. Output characteristics were reproducible to within 1 percent, with minimal hysteresis effects; the average sensitivity was 0.13 mV/Oe·mA, comparable to that of InSb Hall sensors, while the output temperature coefficient was -0.09 %/°C, superior to InSb devices. The test device was used to read data from a magnetic card, with good results.