Tuning rotational magnetization for high frequency magnetoimpedance in micro-patterned triangle spiral magnetic systems

Abstract

Achieving high sensitivity, resolution, and accuracy is desirable and in high demand for magnetic sensor applications. The giant magnetoimpedance (GMI) effect has drawn intensive attention owing to its ultrasensitive response to the magnetic field. Further enhancement of the GMI effect in soft magnetic conductors (wires, ribbons, or films) is essential but represents a big challenge since the experimentally reported highest GMI ratio is still much smaller than its theoretically predicted value. Inspired by the kirigami structures, we propose a new approach for improving the GMI effect by designing triangle spiral magnetic systems. We demonstrate that the GMI ratio can be easily tuned by varying the edge width of the triangle spiral magnetic ribbon. The GMI ratio is enhanced up to 250% and 100% for the Fe 92.5 C 3.5 Si 3.9 ribbon with a 60 μm wide edge when a magnetic field of 100 Oe is aligned along the altitude and edge directions, respectively. Magnetometry indicates that upon reduction of the edge width, the improvement of magnetic susceptibility at low applied fields is correlated with the strengthened shape anisotropy. Micromagnetic simulations suggest that various closure magnetic domain configurations such as stripe and zig-zag domain structures can be formed, depending on the applied magnetic field directions, as a result of the competition of anisotropy and Zeeman energies followed in the Stoner-Wohlfarth model. The simulated results fully support the experimentally observed GMI enhancement and attribute it to the formation of transverse magnetic domains at the critical dimension of the micro-patterned magnetic ribbon system. These superior properties make the triangle-spiral GMI sensor a promising candidate for advanced sensor applications. • Various branch-width triangle spiral magnetic systems have been developed and characterized, at which optimized 60 μm width showing the best GMI effect owing to the strengthened shape anisotropy. • The GMI effect is augmented up to 250% and 100% under an applied magnetic field of 100 Oe aligned along with the altitude and edge directions, respectively. • The GMI enhancement is supported by transverse domain formations approved by OOMMF micromagnetic simulation. • Wide range of magnetic domain configurations can be formed depending on the applied magnetic field directions, originating from the competition of anisotropy and Zeeman energies followed in the Stoner-Wohlfarth model.