Magnetically directed self-assembly of photonic crystals

应研究由磁性核壳胶体形成三维光子晶体。在磁场梯度的转向力作用下，胶体悬浮液中干燥出亚微米大小的核壳粒子，该粒子由乳胶芯周围的Ti02和Fe304纳米晶层组成。这种方法允许使用不同的场梯度和边界条件来研究凝聚和结构相变。磁性和光学性质由对位和铁磁共振和光学光谱学确定。光刻预制图案化的硅衬底被用来稳定用于生长3D胶体晶体的二维种子层。去除乳胶芯是可能的，并且可以获得由于胶体晶体的磁致伸缩变形而产生的磁可调谐光子晶体。

The formation of three-dimensional photonic crystals from magnetic core-shell colloids shall be investigated. Sub-micron sized core-shell particles consisting of layers of Ti02 and Fe304 nanocrystals around a latex core are dried from colloidal suspensions under the steering forces of a magnetic field gradient. This approach allows the study of condensation and structural phase transitions using different field gradients and boundary conditions. Magnetic and optical properties are determined by para- and ferromagnetic resonance and optical spectroscopy. Lithographically pre-patterned silicon substrates are used to stabilize two-dimensional seed layers for the growth of the 3D colloid crystals. Removal of the latex core is possible and magnetically tunable photonic crystal due to magnetostrictive distortions of the colloid crystals may be obtained.