Broadband optical measurement of AC magnetic susceptibility of magnetite nanoparticles

Abstract

Characterization of magnetic nanoparticles in solution is challenging due to the interplay between magnetic relaxation and agglomeration. The AC magnetic susceptibility of magnetite nanoparticles in water has been studied using magneto-optical methods in the frequency range of 10 Hz–250 kHz. The Faraday effect is detected simultaneously with changes in the fluid configuration. It is shown that the relative sensitivity to the magnetic and structural response can be adjusted by varying the wavelength, paving the way toward spatially resolved studies at the micro-scale