Influence of demagnetizing field on thin-film GMI magnetic sensor elements with uniaxial magnetic anisotropy

Hiroaki Kikuchi, Shingo Kamata, Tomoo Nakai, Shuichiro Hashi, Kazushi Ishiyama

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We investigated the dependence of demagnetizing effect on the giant magnetoimpedance (GMI) properties of elements fabricated using a thin film with uniaxial magnetic anisotropy. Using photolithography techniques, we fabricated two types of sensor elements. One type has a typical GMI configuration, i.e., the easy axis is parallel to the width of the sensor element, whereas the other type has an inclined easy axis. In sensors with a typical GMI configuration, the impedance changes and sensitivity at the edges of the elements are reduced relative to the middle sections, whereas the discontinuous impedance jump is substantially reduced or modified in sensors with inclined easy-axis GMI elements. This divergence in behavior can be explained by the differences in the distribution of demagnetizing fields within the respective element types. Because the demagnetizing field has an increased gradient of growth at the edge of an element, rotation or movement of the magnetization moment becomes increasingly modified. We confirmed the changes in the distribution of the demagnetizing field within the element using magnetic-field analysis and confirmed by domain observation that nonuniform magnetic domain movement occurs at the edge of the element. The change in the direction-to-gain ratio associated with higher element sensitivity is also discussed, and a method to effectively utilize the discontinuous jump is introduced. Only the central part of the element should be used to eliminate the influence due to the distribution of the demagnetizing field.

Original languageEnglish
Pages (from-to)142-149
Number of pages8
JournalSensors and Actuators, A: Physical
Volume230
DOIs
Publication statusPublished - 2015 May 22

Keywords

  • Demagnetizing field
  • Discontinuous jump
  • Giant magnetoimpedance
  • Impedance change
  • Sensitivity
  • Uniaxial anisotropy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering

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