Magnetic field induced extinction of light in a suspension of Fe3O4 nanoparticles

Abstract

We report magnetic field induced extinction of light in Mie regime using a magnetic nanofluid containing Fe3O4 nanoparticles of 6.7nm. At a critical applied magnetic field (HC2), the transmitted light intensity becomes extinct where the HC2 follows a power law decay with volume fraction of nanoparticles (HC2∞ϕ−x, where x=0.283) indicating a structural transition. The light transmission was reversible with the magnetic field. We discuss various possible mechanisms responsible for the extinction of light under external magnetic field. The experimental finding may have significant application in tunable light controlling devices.