Long-time annealing and activation energy of the interdiffusion at AlO x/Co-Fe/Ir-Mn interfaces

Yoshiaki Saito, Minoru Amano, Katsuya Nishiyama, Yoshiaki Asao, Kenji Tsuchida, Hiroaki Yoda, Shuichi Tahara

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Dual-spin-valve-type double magnetic tunnel junctions (double MTJs) of sputtered Ir-Mn/CoFe/AlOx/CoFeNi/AlOx/CoFe/Ir-Mn were fabricated using photolithography and ion-beam milling. The double MTJs were subjected to long-time annealing at various temperatures (185-400°C) in order to investigate the thermal stability due to the interdiffusion. Magnetoresistance (MR) ratio and resistance were measured at room temperature before and after annealing. The thermal changes of MR ratio are well-explained by considering three phenomena with effective activation energies of 2.6 eV, 0.26 eV, and 1.9eV. These values are in good agreement with the activation energies of the interdiffusion based on the vacancy mechanism. The three phenomena with the effective activation energies are well-explained by considering the interdiffusion and redistribution of O and Mn at the AlO x/Co-Fe/Ir-Mn interfaces. Based on the effective activation energies, it is evaluated that there would be no significant changes in the MR ratio in MTJs with CoFe(3 nm)/IrMn pinned layers for a period of more than 10 years at 160°C.

Original languageEnglish
Pages (from-to)2484-2488
Number of pages5
JournalJapanese Journal of Applied Physics
Issue number5 A
Publication statusPublished - 2004 May


  • Activation energy
  • AlO/CoFe/IrMn interfaces
  • Annealing temperature
  • Annealing time dependence
  • Electron transport in interface structures
  • Interdiffusion
  • Magnetic tunnel junctions
  • Thermal stability


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