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MA: Fachverband Magnetismus

MA 17: Poster Session I

MA 17.22: Poster

Dienstag, 8. März 2016, 09:30–12:30, Poster B1

Tuning of aspect ratio and magnetic material parameters for pronounced flux closure in giant magnetoimpedance (GMI) sensors — •Gregor Büttel, Julian Joppich, and Uwe Hartmann — Institute of Experimental Physics, Saarland University, D66041, Saarbrücken, Germany

It is well known that sputter-deposited Permalloy (Py) shows a strong perpendicular anisotropy above a critical thickness destroying its soft magnetic properties needed for GMI-based magnetic field sensors. Therefore many groups use a multilayer system with a non-magnetic spacer to prevent the appearance of stripe domains and a wide hysteresis curve. We have studied the magnetic properties and microstructure of such micrometer-sized structures sputtered from targets of slightly different Ni:Fe ratio while analyzing target and sample composition by EDX. Different spacer materials are investigated for their influence on strong flux closure of the magnetic layers by MOKE microscopy and MFM. We find that the target ratio strongly determines the critical thickness and at a Ni:Fe ratio of around 79:21 a film can be deposited up to 1000 nm showing neither stripe domains nor columnar microstructure. This is interesting for GMI thin film sensors, as multilayer systems show a weaker flux closure and complicated domain structures compared to Py/spacer/Py layer systems in our micromagnetic simulations and measurements.