The effect of external magnetic field on the SPR phenomenon in modified Kretschmann configuration using magnetic cobalt ferrite nanoparticles

An effect of external magnetic field on surface plasmon resonance (SPR) phenomenon has been studied using cobalt ferrite nanoparticles on silver-Kretschmann configuration. The cobalt ferrite (CoFe2O4) nanoparticles with the size of about 4 nanometers were synthesized by a coprecipitation method. The SPR system was applied by an external magnetic field in various directions to monitor the change of SPR phenomenon. The attenuated total reflection (ATR) curve shows that the SPR angle shifts to different directions depending on the external magnetic field direction. The SPR angle shift may be caused by the superparamagnetic property of cobalt ferrite nanoparticles. The magnetic moment of cobalt ferrite has free movement in single domain of nanoparticles and can be controlled by the external magnetic field. The direction of magnetic moment changes homogenously following the external magnetic field and it probably influences the refractive index of cobalt ferrite nanoparticles.