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Highly Tunable Superparamagnetic Colloidal Photonic Crystals


  • Y.Y. thanks the University of California, Riverside, for start-up funds and Dr. C. K. Erdonmez for helpful discussions. We thank Prof. W. P. Beyermann and Dr. M. Biasini for help with magnetic-property measurements and Dr. Bozhilov and Mr. McDaniel at the Central Facility for Advanced Microscopy and Microanalysis at UCR for assistance with TEM analysis.


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Tuning crystal: Superparamagnetic nanocrystal clusters can self-assemble into colloidal photonic crystals in solution, whose stop bands can be magnetically tuned across the entire visible spectrum. Owing to the high magnetization and the highly charged polyacrylate-capped surface of each cluster, the colloidal photonic crystals show a rapid, reversible, and widely tunable optical response to external magnetic fields.