Granular Hall Sensors for Scanning Probe Microscopy

Scanning Hall probe microscopy is attractive for minimally invasive characterization of magnetic thin films and nanostructures by measurement of the emanating magnetic stray field. Established sensor probes operating at room temperature employ highly miniaturized spin-valve elements or semimetals, such as Bi. As the sensor layer structures are fabricated by patterning of planar thin films, their adaption to custom-made sensor probe geometries is highly challenging or impossible. Here we show how nanogranular ferromagnetic Hall devices fabricated by the direct-write method of focused electron beam induced deposition (FEBID) can be tailor-made for any given probe geometry. Furthermore, we demonstrate how the magnetic stray field sensitivity can be optimized in situ directly after direct-write nanofabrication of the sensor element. First proof-of-principle results on the use of this novel scanning Hall sensor are shown.

Automated summary

Scanning Hall probe microscopy is used for minimally invasive characterization of magnetic thin films and nanostructures by measuring the emanating magnetic stray field. Sensor probes typically use highly miniaturized spin-valve elements or semimetals. Nanogranular ferromagnetic Hall devices fabricated by direct-write method can be tailor-made for any probe geometry and the magnetic stray field sensitivity can be optimized in situ.