Detection of sub-nano-tesla magnetic field by integrated magnetic tunnel junctions with bottom synthetic antiferro-coupled free layer

Kosuke Fujiwara, Mikihiko Oogane, Takuo Nishikawa, Hiroshi Naganuma, Yasuo Ando

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

Arrays of 100 × 100 magnetic tunnel junctions (MTJs) connected in parallel and series were fabricated. A synthetic antiferro-coupled bottom free layer with a NiFe/Ru/CoFeB structure and MgO tunneling barrier were used to realize a high sensitivity, which is defined as TMR/2Hk, where, TMR is the tunneling magnetoresistance ratio and Hkis the magnetic anisotropy field of the free layer. To obtain a linear response of tunneling resistance against an applied external magnetic field, a double annealing process was carried out. From R-H curve measurements, the sensitivity of the 100 × 100 integrated MTJs was lower (8%/Oe) than that of a single MTJ (25%/Oe). However, a 1/30 decrease in noise power density was realized in the integrated MTJs. Consequently, a very small magnetic field of 0.29 nT was detected with the integrated MTJs.

Original languageEnglish
Article number04CM07
JournalJapanese journal of applied physics
Volume52
Issue number4 PART 2
DOIs
Publication statusPublished - 2013 Apr

ASJC Scopus subject areas

  • Engineering(all)
  • Physics and Astronomy(all)

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