Browsing by Author "Wang, Liang-Wei"

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Sharp variation in coercivity and magnetic interactions in patterned CoxNi1-x nanoarrays
(2013-08-14)
Yang, Chao-Yao
;
Wang, Liang-Wei
;
Chen, Po-An
;
Lin, Hong-Ji
;
Lai, Chih-Huang
We present a study concerning the unexpectedly large coercivity increase and associated magneto-structural properties of CoxNi1-x patterned arrays. An increase in x led to an face-center-cubic (FCC)-> hexagonal-close-packed (HCP) transition in CoxNi1-x arrays, accompanied by a 6-fold increase in coercivity and strong 3d exchange interactions probed by x-ray magnetic circular dichroism. Sum-rule analysis revealed that orbital moment involved very little in the variable coercivity and magnetic anisotropy; this is distinct from other nanostructures displaying variable coercivity. The sharp rise in coercivity can be attributed to the geometrical confinement of the arrays, causing the microstructure of the nano-clusters to switch magnetization reversal mechanism from fanning to coherent with increasing x, based on the chain-of-spheres model. First-order-reversal curves revealed that the FCC and HCP arrays comprised both soft and hard ferromagnetic components; however, the soft component of the FCC was much more pronounced, leading to differences in reversibility. This type of nanostructure provides a sharp control of magnetic hardness that could be tailored in related technologies. (C) 2013 AIP Publishing LLC.