Yoke-shaped sensors based on MgO-barrier magnetic tunnel junctions have been designed, fabricated, and studied; they show a good linear tunneling magnetoresistance (TMR) response. A nearly-perpendicular configuration of two ferromagnetic electrodes was set by two-step annealing together with shape anisotropy. The low-frequency noise characterization shows these yoke-shaped TMR sensors have relatively low magnetic 1/f noise. The field sensitivity is up to 27%/mT, while the field detectivity reaches 4.6 nT / Hz at 10 Hz and 460 pT / Hz at 1 kHz. These TMR sensors may be useful for applications such as biomagnetic detection.
Bibliographical noteFunding Information:
The authors thank Bo Cui from University of Waterloo, Canada, K. Oguz, H. Kurt, and D. Ménard for helpful discussions. The work was supported by the EU as part of FP7 NAMDIATREAM Project and by Science Foundation Ireland as part of the Nanoscale Interface and Spin Electronics (NISE) Project (10/IN1/I3006).