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 journalArticle

209 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 Dec 1

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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