Investigation on the magnetization reversal of Nanostructured magnetic tunnel junction rings

C. C. Chen, J. Y. Lin, Lance Horng, J. S. Yang, S. Isogami, M. Tsunoda, Migaku Takahashi, J. C. Wu

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Nanostructured magnetic tunnel junction rings (MTJ) based on CoFeB free layer were fabricated to investigate the corresponding magnetization reversal processes. The dimensions of the MTJ rings were with outer diameter/linewidth of 1 μm/100 nm and 0.7μm/100 nm, respectively, in which the fabrication was carried out by a top-down technique in combination with electron beam lithography, ion-milling and etch-back processes. Double transition processes in magnetoresistance (MR) responses are observed in these nanostructured MTJ rings. With considering the surface roughness, an OOMMF simulation was employed to explore the magnetization evolution. The simulated hysteresis loops are consistent with the MR behaviors, unfolding that the magnetic switching process initiates from the forward to reversed onion states through an incomplete vortex state. This two-step switching behavior is reasonably assumed to be due to a pinning site resulting from the surface roughness in a region of the ring. In addition, a series of in situ magnetic force microscopy images extracted from nanostructured MTJ rings reveals the similar magnetization evolution with the simulated results.

Original languageEnglish
Article number5257327
Pages (from-to)3546-3549
Number of pages4
JournalIEEE Transactions on Magnetics
Issue number10
Publication statusPublished - 2009 Oct


  • Magnetic force microscopy (MFM)
  • Magnetic tunnel junctions (MTJs)
  • Magnetization reversal
  • Magnetoresistance
  • Ring

ASJC Scopus subject areas

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


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