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Micromagnetic Simulations of Submicron Vortex Structures for the Detection of Superparamagnetic Labels

We present a numerical investigation on the detection of superparamagnetic labels using a giant magnetoresistance (GMR) vortex structure. For this purpose, the Landau–Lifshitz–Gilbert equation was solved numerically applying an external z-field for the activation of the superparamagnetic label. Initially, the free layer’s magnetization change due to the stray field of the label is simulated. The electric response of the GMR sensor is calculated by applying a self-consistent spin-diffusion model to the precomputed magnetization configurations. It is shown that the soft-magnetic free layer reacts on the stray field of the label by shifting the magnetic vortex orthogonally to the shift direction of the label. As a consequence, the electric potential of the GMR sensor changes significantly for label shifts parallel or antiparallel to the pinning of the fixed layer. Depending on the label size and its distance to the sensor, the GMR sensor responds, changing the electric potential from 26.6 mV to 28.3 mV.

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Gefördert durch den Publikationsfonds der Universität Kassel
Citation
In: sensors Volume 20 / Issue 20 (2020-10-15) , S. ; EISSN 1424-8220
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@article{doi:10.17170/kobra-202011162175,
  author    ={Wetterau, Lukas and Abert, Claas and Suess, Dieter and Albrecht, Manfred and Witzigmann, Bernd},
  title    ={Micromagnetic Simulations of Submicron Vortex Structures for the Detection of Superparamagnetic Labels},
  keywords ={550 and 600 and Mikrosystemtechnik and Mikromagnetismus and Paramagnetismus and Simulation and Lab on a Chip},
  copyright  ={http://creativecommons.org/licenses/by/4.0/},
  language ={en},
  journal  ={sensors},
  year   ={2020-10-15}
}