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Nature Materials 7, 567–573 (1 July 2008) | doi:10.1038/nmat2204

Sidewall oxide effects on spin-torque- and magnetic-field-induced reversal characteristics of thin-film nanomagnets

O. Ozatay , P. G. Gowtham , K. W. Tan , J. C. Read , K. A. Mkhoyan , M. G. Thomas , G. D. Fuchs , P. M. Braganca , E. M. Ryan , K. V. Thadani , J. Silcox , D. C. Ralph & R. A. Buhrman

The successful operation of spin-based data storage devices depends on thermally stable magnetic bits. At the same time, the data-processing speeds required by today|[rsquo]|s technology necessitate ultrafast switching in storage devices. Achieving both thermal stability and fast switching requires controlling the effective damping in magnetic nanoparticles. By carrying out a surface chemical analysis, we show that through exposure to ambient oxygen during processing, a nanomagnet can develop an antiferromagnetic sidewall oxide layer that has detrimental effects, which include a reduction in the thermal stability at room temperature and anomalously high magnetic damping at low temperatures. The in situ deposition of a thin Al metal layer, oxidized to completion in air, greatly reduces or eliminates these problems. This implies that the effective damping and the thermal stability of a nanomagnet can be tuned, leading to a variety of potential applications in spintronic devices such as spin-torque oscillators and patterned media.