The effects of post-deposition ion-beam bombardment with oxygen on the Co surface in modifying the magnetic properties of Co thin films

X. Li, K. W. Lin, H. T. Liang, P. L. Liu, W. C. Lo, D. L. Cortie, F. Klose, J. Van Lierop, L. Li, Philip W.T. Pong

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Ion beam bombardment is a useful surface modification method in tailoring the microstructure and magnetic properties of ferromagnetic thin films. In this paper, Co thin films were bombarded by Ar+ ion beam with oxygen and then capped with Al (to prevent oxidation). The oxygen content was altered from 0 to 41% to investigate the ion-beam bombardment effect. An oxide layer containing Al2O3, Co3O4 and CoO was formed after the ion-beam bombardment with oxygen, as characterized by x-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, selected area electron diffraction, and x-ray diffraction. Enhanced coercivities (Hc's) (from 4.14 kA/m to 7.96 kA/m) and loop squareness (Mr/Ms. from 0.5 to 0.8) was induced by pure Ar+ ion-beam bombardment that resulted in domain wall pinning due to bombardment-induced defects and Co spin reordering. Hc exhibited a strong dependence on the oxygen content in the ion beam, due to the nature of the cobalt oxide formation. Field cooling to 180 K resulted in increased squareness (Mr/Ms. = 0.9) and reduced Hc. The low-field magnetization measured during zero field and field cooling to further investigate the exchange bias magnetism identified an irreversibility temperature at 320 K in a film treated by ion-beam bombardment with an O2/Ar ratio of 21%.

Original languageEnglish (US)
Pages (from-to)41-47
Number of pages7
JournalMicroelectronic Engineering
Volume152
DOIs
StatePublished - Feb 20 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrical and Electronic Engineering

Keywords

  • Cobalt
  • Ion-beam bombardment
  • Magnetic property

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