2-Axis Magnetometers Based on Full Wheatstone Bridges Incorporating Magnetic Tunnel Junctions Connected in Series

Full Wheatstone Bridge incorporating a serially connected ensemble of Magnetic tunnel junctions was produced, targeting an application as a magnetic field compass. To that end, MTJs with
${\rm RxA}\sim 10\ {\rm k}\Omega\ \mu{\rm m}^{2}$
,
${\rm TMR}\sim 150$
–200%,
${\rm Hf}=5\ {\rm Oe}$
and
${\rm Hf}=5\ {\rm Oe}$
were produced. In order to achieve a full bridge signal, two stacks with an asymmetric SAF reference structure where used to produce MTJs with opposite dR/dH upon annealing in the same substrate. The resulting Bridges exhibit sensitivities between 13.5–32 mV/V/Oe depending on the field range and provide a significantly advantageous alternative to AMR and GMR based bridges.