Magnetoresponsive Photonic Microspheres with Structural Color Gradient

Researchers report a simple but robust method to create photonic microspheres with a gradient of structural color and magnetic anisotropy, which enables the microspheres to display multiple structural colors depending on their orientation. To design the photonic nanostructure with a gradient of periodicity, the researchers repeatedly deposit thin layers of silica and titania on the black microspheres. The high directionality of the sputtering deposition yields the 1D photonic structure, in which the thickness decreases along the curved surface of the microspheres from the north pole.