Field induced photonic bandgap in ferrodispersion

A stable dispersion of micron size magnetite spheres in a ferrofluid exhibits several interesting magnetically induced effects like zero forward scattering, enhanced backward scattering etc. Here we show that at a critical magnetic field the dispersion inhibits propagation of certain optical frequencies. The field required to induce this photonic band gap is quite moderate and the technique can be easily adopted for lab-on-chip devices.