Thermally stable exchange-biased magnetic tunnel junctions over 400 °C

Matsukawa, Nozomu; Odagawa, Akihiro; Sugita, Yasunari; Kawashima, Yoshio; Morinaga, Yasunori; Satomi, Mitsuo; Hiramoto, Masayoshi; Kuwata, Jun
December 2002
Applied Physics Letters;12/16/2002, Vol. 81 Issue 25, p4784
Academic Journal
Exchange-biased magnetic tunnel junctions (MTJs) with interposed Fe[sub 1 - x]Pt[sub x] metal alloy layers between the Al oxide barrier and the ferromagnetic electrodes maintain large tunneling magnetoresistance (TMR) after thermal treatment in excess of 400 °C, owing to an improved barrier interface. After 400°C annealing, TMRs of MTJs with Fe[sub 1 - x]Pt[sub x] (x=0.1-0.2) exhibit over 40% and retain 30% TMR after 420 °C annealing. The tunnel barrier height derived from the currentvoltage curve fitted to the Simmons equation increases with richer Pt content. Secondary ion mass spectroscopy depth profiles and cross-section transmission electron micrographs of MTJs with Fe[sub 0.85]Pt[sub 0.15] show a clear interface around the Al oxide barrier even after annealing at 400°C.


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