Influence of heavy ion irradiation on perpendicular-anisotropy CoFeB-MgO magnetic tunnel junctions

Daisuke Kobayashi, Yuya Kakehashi, Kazuyuki Hirose, Shinobu Onoda, Takahiro Makino, Takeshi Ohshima, Shoji Ikeda, Michihiko Yamanouchi, Hideo Sato, Eli Christopher Enobio, Tetsuo Endoh, Hideo Ohno

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


A non-volatile memory element called a perpendicular-anisotropy magnetic tunnel junction was fabricated using CoFeB/MgO/CoFeB film stack technology. It exhibits two stable resistance values, high or low, depending on the relative directions of the magnetizations of the two ferromagnetic CoFeB layers. After being programmed into the high resistance state with a current injection scheme based on the spin transfer torque theory, the tunnel junction was exposed to 15-MeV Si ions under different voltage stress conditions. The tested structure remained in the programmed high resistance state after being bombarded with 10-100 Si ions, even under the stressed situations. A time-domain analysis proved that this result is due to the perfect immunity of the tested magnetic tunnel junction to single event upsets. Some degradation in resistance due to the heavy-ion irradiation was detected through a precise parameter analysis based on a tunneling theory but it was negligibly small (1%). There were no statistically significant changes in the thermal stability factor before and after irradiation, and this means the long-term retention properties remained unchanged.

Original languageEnglish
Article number6804706
Pages (from-to)1710-1716
Number of pages7
JournalIEEE Transactions on Nuclear Science
Issue number4
Publication statusPublished - 2014 Aug


  • Ion radiation effects
  • MRAM
  • magnetoresistive devices
  • perpendicular magnetic anisotropy
  • single event upsets
  • soft errors
  • spin polarized transport
  • tunneling magnetoresistance

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering


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