Tunable magnetic order of Co nanoparticles and magnetotransport in Co/ZnO nanocomposites

Hsu, C. Y.; Huang, J. C. A.; Chen, S. F.; Liu, C. P.; Sun, S. J.; Tzeng, Yonhua
August 2008
Applied Physics Letters;8/18/2008, Vol. 93 Issue 7, p072506
Academic Journal
We demonstrate tunable magnetic order of cobalt nanoparticles in Co/ZnO nanocomposites. High-density electronic states in ZnO formed during high vacuum annealing help generate bound and free charge carriers, which in turn enable the stable magnetic ordering of Co nanoparticles in the Co/ZnO nanocomposites in a tunable manner. This is demonstrated by the following experimental observations: (i) enhanced spontaneous magnetization and coercivity, (ii) transition from semiconducting to metallic electrical-transport, and (iii) transverse magnetotransport transition from negative magnetoresistance to the anomalous Hall effect. The work explores a route to manipulate the magnetic order of magnetic nanoparticles by means of intentionally generated defects in oxides.


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