Regensburg 2022 – scientific programme

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MA: Fachverband Magnetismus

MA 35: Poster 2

MA 35.63: Poster

Thursday, September 8, 2022, 16:00–18:00, P4

Giant and Tunneling Magnetic Resistance sensor elements based on Focused Ion Beam methods and chemical synthesis — •Laila Bondzio, Björn Büker, Nadine Fokin, Pierre Piel, and Andreas Hütten — University of Bielefeld, Germany

Common GMR and TMR sensors are based on sputter deposited multilayer stacks. Structuring these thin films using lithography can be expensive and time consuming, thus alternative ways of structuring are explored such as nanoparticle synthesis or high-precision milling via ion beam.

A dual-beam Focused Ion Beam (FIB) microscope can be used for Focused Electron Beam Induced Deposition (FEBID) to deposit small Co dots as nanoparticles, which are afterwards covered with a slightly conductive material to fill the gaps, so that a granular highly ordered, 2 dimensional GMR array is created in a bottom-up method. Alternatively, the ion beam can be used for a top-down approach by milling grid-like structures into a deposited magnetic layer to create rectangular particles. In spite of successful proof of concept measurements, higher particle densities are needed to produce a sufficiently high effect for sensor applications.

With chemical nanoparticle synthesis arrays of randomly arranged nanoparticles can be created representing the ferromagnetic layers. The organic ligand shells of e.g. oelic acid create the isolated TMR barrier between the particles. Measurements on these otherwise untreated random, 3 dimensional particle arrays have shown a broad TMR curve for high fields.