Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 9: Anisotropy/Magnetoelasticity

MA 9.2: Talk

Monday, March 26, 2007, 17:30–17:45, H22

Effects of uniaxial stress on the properties of giant magnetoresistive sensors on polyimide substrates — •Berkem Özkaya, Srinivasa Rao Saranu, Senthilnathan Mohanan, and Ulrich Herr — Institute for Micro and Nanomaterials, University of Ulm, D-89081, Germany.

The change in the sensitivity of giant magnetoresistive (GMR) sensors on polyimide substrate was demonstrated. Applying uniaxial stress on magnetic layers leads to stress induced anisotropy. Initially, we investigated stress effects on single Co thin film prepared by DC magnetron sputtering, which exhibits macroscopic in-plane easy axis induced by the preparation process. In-situ magnetisation curves in the stressed state were obtained by using MOKE magnetometer. When stress is applied perpendicular to induced in-plane easy axis, coercivity field (Hc) and remanent magnetisation (Mr) are decreasing, and saturation field (Hs ) is increasing. For [Cu/Co]15 multilayer exhibiting ~20% GMR value, it is observed that when the stress is applied parallel to the external magnetic field (Hext), Hs is increasing and the GMR remains constant, resulting in a reduced sensitivity. On the other hand, when the stress is applied perpendicular to Hext, we observed that Hs is decreasing and the GMR remains constant, resulting in a increased sensitivity. For trilayer system of Co/Cu/Ni in which Co is positive and Ni is negative magnetostrictive layer, applying stress leads to reverse rotation of magnetisation in both magnetic layers. When the stress is applied parallel to Hext, the GMR is decreasing, and Hs is increasing, resulting in a reduced sensitivity.