6533b853fe1ef96bd12acd4a

RESEARCH PRODUCT

Geometrical dependence of domain wall propagation and nucleation fields in magnetic domain wall sensor devices

H. GrimmJ. WahrhusenB. BorieAndreas KehlbergerMathias Kläui

subject

Materials scienceMagnetic domainNucleationGeneral Physics and AstronomyFOS: Physical sciencesField strength02 engineering and technologyApplied Physics (physics.app-ph)01 natural sciencesElectrical resistance and conductance0103 physical sciencesMesoscale and Nanoscale Physics (cond-mat.mes-hall)010302 applied physicsCondensed Matter - Materials ScienceCondensed Matter - Mesoscale and Nanoscale Physicsbusiness.industryMaterials Science (cond-mat.mtrl-sci)Physics - Applied Physics021001 nanoscience & nanotechnologyMagnetic fieldPower (physics)Domain wall (magnetism)OptoelectronicsDevelopment (differential geometry)0210 nano-technologybusiness

description

We study the key domain wall properties in segmented nanowires loop-based structures used in domain wall based sensors. The two reasons for device failure, namely the distribution of domain wall propagation field (depinning) and the nucleation field are determined with Magneto-Optical Kerr Effect (MOKE) and Giant Magnetoresistance (GMR) measurements for thousands of elements to obtain significant statistics. Single layers of Ni$_{81}$Fe$_{19}$, a complete GMR stack with Co$_{90}$Fe$_{10}$/Ni$_{81}$Fe$_{19}$ as a free layer and a single layer of Co$_{90}$Fe$_{10}$ are deposited and industrially patterned to determine the influence of the shape anisotropy, the magnetocrystalline anisotropy and the fabrication processes. We show that the propagation field is little influenced by the geometry but significantly by material parameters. The domain wall nucleation fields can be described by a typical Stoner-Wohlfarth model related to the measured geometrical parameters of the wires and fitted by considering the process parameters. The GMR effect is subsequently measured in a substantial number of devices (3000), in order to accurately gauge the variation between devices. This reveals a corrected upper limit to the nucleation fields of the sensors that can be exploited for fast characterization of working elements.

https://dx.doi.org/10.48550/arxiv.1704.07371