Magnetic Tunneling Junction based Sensors for Bio-detection Applications

ORAL

Abstract

Magnetic tunneling junctions are capable of sensing very weak magnetic fields at room temperature. It is a suitable device to detect a biomolecule which is tagged with magnetic nanoparticles. We have designed and developed Al2O3- and MgO- based MTJ sensors using microfabrication techniques. The study reveals that in the case of Al2O3-based sensors the shape anisotropy in the free magnetic electrode results in a linear and hysteresis free magnetoresistance (MR) curve. Moreover, Al2O3 based sensor have 28{\%} TMR and sensitivity of up to 0.4 {\%}/Oe over a magnetic field range of $\pm $ 40 Oe. In the case of MgO-based sensors, there are two possible methods to achieve a linear and hysteresis free MR response. One can increase the aspect ratio in free magnetic electrode, alternatively, one can use superparamagnetic free layer. MgO-based sensor has about 90{\%} TMR and sensitivity of 1.1 {\%}/Oe over the field range of $\pm $ 40 Oe.

*This work is supported by DOE No. DE-FG02-07ER46374.

Authors

  • L.R. Shah

    • University of Delaware
    • Department of Physics and Astronomy, University of Delaware
    • Physics and Astronomy, University of Delaware, Newark DE, 19716

  • N. Bhargava

    • Electrical and Computer Engineering, University of Delaware, Newark DE, 19716

  • S. Kim

    • Electrical and Computer Engineering, University of Delaware, Newark DE, 19716

  • J. Kolodzey

    • Electrical and Computer Engineering, University of Delaware, Newark DE, 19716

  • K. Cheng

    • Department of Chemistry, Brown University, Providence RI, 02912

  • S. Sun

    • Department of Chemistry, Brown University, Providence RI, 02912

  • R. Stearret

    • Physics and Astronomy, University of Delaware, Newark DE, 19716

  • X. Kou

    • Physics and Astronomy, University of Delaware, Newark DE, 19716

  • E.R. Nowak

    • Physics and Astronomy, University of Delaware, Newark DE, 19716

  • J.Q. Xiao

    • Physics and Astronomy, University of Delaware, Newark DE, 19716