Stray field and combined effects on device miniaturization of the magnetic tunnel junctions

Chih Wei Cheng, Kuan Ming Chen, Jeng Hua Wei, Yu Chen Hsin, Shyh Shyuan Sheu, Chih I. Wu, Yuan Chieh Tseng*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Magneto-static stray field (H stray) interactions become an important issue when perpendicular CoFeB/MgO magnetic tunnel junctions (MTJs) are miniaturized. This raises the issue of which of the two mainstream etching processes, the pillar structure and the step structure, is better able to retain MTJ performance at extremely small scales. In the current study, we first simulated H stray effects as a function of Ruderman-Kittel-Kasuya-Yosida strength within a synthetic antiferromagnetic structure for the two structures. Our results revealed that H stray interactions were less influential (in terms of offset field) in step MTJs than in pillar MTJs during MTJ miniaturization. This is in good agreement with experimental results. This finding is further supported by adding Dzyaloshinskii-Moriya interactions into the free-layer of the two structures. We further simulated thermal stability with the inclusion of H stray for 30 nm MTJs. We found that adding etching damage effects (i.e. assuming both anisotropy constant and saturation magnetization of the free layer had some degree of loss) into the model of the pillar MTJ was necessary to obtain a trend that is close to the experimental results of thermal stability. This information can provide some guidance on the technical choices for the MTJ miniaturization.

Original languageEnglish
Article number195002
JournalJournal of Physics D: Applied Physics
Volume55
Issue number19
DOIs
StatePublished - 12 May 2022

Keywords

  • Dzyaloshinskii-Moriya interactions
  • magnetic tunnel junction
  • micromagnetic simulation
  • sidewall etching damage
  • spin-transfer torque
  • stray field

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