Switching Field Control by Utilizing Ferromagnetic Grain Boundary in Cap Layer for CoPt-Based Full Granular Media

Kim Kong Tham, Ryosuke Kushibiki, Tomonari Kamada, Shin Saito

Research output: Contribution to journalArticlepeer-review

Abstract

Investigation of magnetic properties and nanostructure for full granular media with CoPt-Gd2O3 granular cap layers (CLs) of various Gd2O3 content were conducted. Media with low surface roughness of 0.19 nm is maintained even though Gd2O3 content is reduced from 30 to 5 vol%, which is lower than that of media with CoPtCrB continuous CL. The result is supported by surface morphology observed by transmission electron microscopy. According to cross section element analysis, homogeneous nanostructure in the thickness direction with one- text on-one columnar growth of magnetic grain is observed. Reduction of Gd2O3 content increases indirect intergranular exchange coupling through CL which results in media with higher nucleation field and lower saturation field than that of media with CoPtCrB continuous CL. Furthermore, at a CL thickness of 6 nm, when Gd2O3 content is reduced from 30 to 15 vol%, switching field distribution is reduced from 0.11 to 0.05. These results suggest that the reduction of Gd2O3 content of the CoPt-Gd2O3 granular CL is effective to reduce the switching field distribution of the full granular media to be lower than that of media with CoPtCrB continuous CL while retaining the extremely smooth media surface.

Original languageEnglish
Article number9158335
JournalIEEE Transactions on Magnetics
Volume57
Issue number2
DOIs
Publication statusPublished - 2021 Feb

Keywords

  • Extremely flat surface
  • ferromagnetic oxide
  • full granular media
  • granular cap layer (CL)
  • narrow switching field distribution

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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