Annealing effect on low-resistance ferromagnetic tunnel junctions

Yasuo Ando, Hitoshi Kubota, Masamitsu Hayashi, Makoto Kamijo, Kazuya Yaoita, Andrew Chak Chung Yu, Xiu Feng Han, Terunobu Miyazaki

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30 Citations (Scopus)


The stacking structure and fabrication process of tunnel junctions were investigated. The stacking structure of the tunnel junctions fabricated was Ta/(Cu,Pt)/Fe20Ni80/IrMn/Co75Fe25/Al- oxide/Co75Fe25/Fe20Ni80/Ta. When the Al thickness, oxidation time, and annealing temperature were 0.8 nm, 15s (10s), and 300°C (250°C), the tunnel magnetoresistance (TMR) ratio and the resistance obtained were 49% (31%) and 1.1 kΩμm2 (230Ωμm2), respectively. In order to investigate the annealing temperature dependence of the TMR ratio, the local electrical properties were measured for a Ta/Fe20Ni80/Pt/Fe20Ni80/IrMn/Co75Fe25/Al- oxide multilayer. The current image became very homogeneous after annealing at around 300°C for 1 h. The increase of the TMR ratio of the junction after annealing can be well explained by taking into account both an increase of barrier height and a decrease of barrier height fluctuation. After further annealing at above 350°C, the barrier height decreased and leakage currents were detected.

Original languageEnglish
Pages (from-to)5832-5837
Number of pages6
JournalJapanese Journal of Applied Physics
Issue number10
Publication statusPublished - 2000 Oct


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