. . . . . . . . . .    ANM 2010     3rd International Conference on Advanced Nano Materials     12-15 September 2010 - Agadir, Morocco Back    Abstract ANMM128  TUNNELING MAGNETORESISTIVE SENSORS EMPLOYED IN HIGHLY SENSITIVE MAGNETIC PARTICLES DETECTION Camelia Albon, Peter Hedwig, Alexander Weddemann, Alexander Auge, Karsten Rott, Andreas Hütten Department of Physics, Thin Films and Physics of Nanostructures, Bielefeld University, PB 100131, 33501 Bielefeld, Germany . The advances realized in the field of spintronics opened new avenues for the development of magnetoresistive sensors. The sensing resolution can be maximized if the size of the MgO based magnetic tunnel junctions (MTJ) is downscaled to the submicron dimensions of magnetic particles. The output of the sensor is linearized when the two ferromagnetic electrodes of the MTJ have an orthogonal orientation of magnetization. This is accomplished by pinning the bottom ferromagnetic electrode of the sensor along the hard (transversal) axis of the elliptical element, while the top detection ferromagnetic electrode will take the orientation of the easy (longitudinal) axis of the element.When CoFeB material is used as top detection layer, the sensor exhibits a linearity in the ± 500 Oe range and a sensitivity of up to 0.1 %/Oe. Within this configuration, the static detection of 1 micrometer magnetic beads and of 14 nm Co nanoparticles is achieved with a very high spatial resolution. With Co2FeSi Heusler compound  as top ferromagnetic electrode, the linearity range of the sensor is increased from -800 to +400 Oe and the sensitivities values are up to 0.03 %/Oe. Future perspectives related to sensors development includes high resolution detection of a single magnetic particle trajectory that flows in a microchannel above the magnetoresistive sensors. . © nanoAC . . . . . . . . . .

.