Webinar

GMR based spin valve (SV-GMR) sensors were being opted in a variety of linear
field sensing applications. In my PhD work, a comprehensive study is performed on both specular and
nonspecular SV-GMR stacks aiming towards the development of linear field sensor. At the end, an attempt
was made to develop a chip to measure the angle in the range of 0 to 360 deg. Initially, the trends of magnetic
exchange bias in ferromagnetic layers were studied using different AFM materials, and then the spin valve
stacks were optimized. Use of nonmagnetic MgO has resulted in additional benefits on both reversibility
and enhanced stability in specular SVs compared to the conventional SVs. As well, it ascertained reliable
sensing with zero anomalies even at low temperatures, up to 10 K, which is reported for the first time.
Further, bi-directional and differential output in linear field range was attained by aligning spin valve resistive
elements in a Wheatstone bridge configuration. In presence of rotational magnetic field vector, the bridge
yields a sine wave characteristic with a periodicity of 360o. A complete angle sensor chip was then developed
resulting in both sine and cosine outputs.