Magnetic induced optical transmittance study of monodisperse nano-size FePt ferrofluid

In this study, the variation of the transmission of light through the FePt magnetic fluid has been investigated as a function of external magnetic field and incident optical wavelength. The optical transmission of monodisperse nano-size FePt ferrofluid with particle size between 2 and 10 nm have been studied with incident optical wavelengths between 450 and 750 nm and applied magnetic fields up to 225 Oe.The ordered fct FePt phase has high magnetic anisotropy and thus large coercivity up to 1.2 T. The optical transmission spectra were measured by means of a spectrophotometer. The optical transmission increases with decreasing the concentration of FePt. However, under an applied magnetic field, the optical transmission decreases for samples.