Magnetically tunable photonic crystals based on anisotropic nanostructures

1. A method of forming magnetically tunable photonic crystals comprising:

synthesizing precursory nanoparticles with anisotropic shapes, the anisotropic precursory nanoparticles being iron oxyhydroxide (FeOOH) nanorods;

coating the anisotropic precursory nanoparticles with silica to form composite structures;

converting the anisotropic precursory nanoparticles into magnetic nanomaterials through chemical reactions, the chemical reactions including reducing the coated composite structure with reducing agents to render the coated composite structures magnetic; and

assembling the anisotropic magnetic nanoparticles into photonic crystals in a solvent.

2. The method of claim 1 , comprising:

adding tetraethyl orthosilicate into a mixture of distilled water, ethanol, ammonia and anisotropic precursory nanoparticles; and

isolating the coated composite structures by centrifugation.

3. The method of claim 1 , wherein the reducing of the coated composite structure with reducing agents to render the coated composite structures magnetic comprises:

heating the coated composite structures; and

reducing the coated composite structures with the reducing agents to render the coated composite structures magnetic.

4. The method of claim 1 , further comprising:

redispersing the as-reduced magnetic nanoparticles by sonication;

applying a size selection to the magnetic nanoparticles; and

discarding non-dispersible aggregates by centrifugation.

5. The method of claim 1 , comprising:

a solvent for assembling nanoparticles into photonic structures, the solvent being water, ethanol, glycol, and other polar or nonpolar solvents.

6. The method of claim 1 , wherein the synthesizing of the iron oxyhydroxide nanorods comprises:

solution-based synthesis of anisotropic precursory nanoparticles.

7. The method of claim 6 , further comprising:

dissolving iron trichloride in deionized water;

adjusting a concentration of iron cations in the iron trichloride dissolved in the deionized water;

discarding undissolved precipitates after centrifugation from the iron trichloride dissolved in the deionized water to form a supernatant; and

heating the supernatant to form the iron oxyhydroxide nanorods.

8. The method of claim 7 , comprising:

isolating the iron oxyhydroxide nanorods by centrifugation.

9. The method of claim 7 , comprising:

functionalizing a surface of the iron oxyhydroxide nanorods with polyacrylic acid.