Observation of multiple magnetic phases and complex nanostructures in Co implanted amorphous carbon films
Observation of multiple magnetic phases and complex nanostructures in Co implanted amorphous carbon films
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DOI：
10.1016/j.jpcs.2018.12.020
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发表时间：
2019-04
影响因子：
4
通讯作者：
K. Suschke;P. Gupta;Grant V. M. Williams;René Hübner;A. Markwitz;John Kennedy
中科院分区：
文献类型：
--
作者：
K. Suschke;P. Gupta;Grant V. M. Williams;René Hübner;A. Markwitz;John Kennedy
Room temperature implantation of 30 keV Co ions into an amorphous carbon film with a high fluence of 1.2 × 1017Co/cm2results in formation of magnetic nanostructures displaying multiple magnetic phases. Cross-sectional TEM images show formation of Co containing nanoparticles at the surface and near-surface regions of the implanted films. EDXS measurements suggest the nanoparticles to be composed primarily of Co and O at the surface and Co and C in deeper regions. These nanoparticles with differing compositions were observed to be segregated by a thin layer devoid of Co. Magnetic measurements reveal the presence of superparamagnetic behavior from small CoxC nanoclusters with a blocking temperature of 5 K. There is a small fraction of larger CoxC nanoclusters that show magnetic hysteresis even at room temperature. The saturation magnetic moment is as high as 0.51 μB/Co at 2 K and 0.32 μB/Co at room temperature. Spin-disorder is seen with a range of spin glass temperatures below ∼70 K. Our high fluence Co implantation into amorphous carbon has resulted in the formation of complex magnetic nanostructures composed of cobalt, oxygen, and carbon. These nanostructures give rise to multiple magnetic phases such as superparamagnetism, spin glass, ferromagnetism, and possibly antiferromagnetism.
