Dependence of giant tunnel magnetoresistance of sputtered CoFeB/MgO/CoFeB magnetic tunnel junctions on MgO barrier thickness and annealing temperature

Jun Hayakawa, Shoji Ikeda, Fumihiro Matsukura, Hiromasa Takahashi, Hideo Ohno

Research output: Contribution to journalArticlepeer-review

217 Citations (Scopus)

Abstract

We investigated the dependence of giant tunnel magnetoresistance (TMR) on the thickness of an MgO barrier and on the annealing temperature of sputtered CoFeB/MgO/CoFeB magnetic tunnel junctions deposited on SiO2/Si wafers. The resistance-area product exponentially increases with MgO thickness, indicating that the quality of MgO barriers is high in the investigated thickness range of 1.15-2.4 nm. High-resolution transmission electron microscope images show that annealing at 375°C results in the formation of crystalline CoFeB/MgO/CoFeB structures, even though CoFeB electrodes are amorphous in the as-sputtered state. The TMR ratio increases with annealing temperature and is as high as 260% at room temperature and 403% at 5 K.

Original languageEnglish
Pages (from-to)L587-L589
JournalJapanese Journal of Applied Physics, Part 2: Letters
Volume44
Issue number16-19
DOIs
Publication statusPublished - 2005

Keywords

  • CoFeB
  • Crystallization
  • Magnetic tunnel junction
  • MgO barrier
  • Tunnel magnetoresistance effect

ASJC Scopus subject areas

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

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