Magneto-optical properties of BiFeO3 thin films using surface plasmon resonance technique

Indigeneously assembled surface plasmon resonance (SPR) set up has been exploited to study the magnetic field dependent optical properties of BiFeO3 thin films. BiFeO3 thin films have been deposited onto gold (Au) coated glass prism by using pulsed laser deposition technique. The surface plasmon modes in prism/Au/BiFeO3/air structure have been excited in Kretschmann configuration at the interface of Au/BiFeO3 thin films. The SPR reflectance curves obtained for prism/Au/BiFeO3/air structure were utilized to investigate the optical properties of BiFeO3 thin films at optical frequency (λ=633 nm) as a function of applied magnetic field. SPR curves shows a continuous shift towards lower angles with increasing applied magnetic field, which indicate the promising application of ferromagnetic BiFeO3 film as a magnetic field sensor. Complex dielectric constant of deposited BiFeO3 film was determined by fitting the experimental SPR data with Fresnel׳s equations. The variation of complex dielectric constant and refractive index of BiFeO3 film was studied with increase in magnetic field, and the sensitivity of magnetic field sensor was found to be about 0.52 RIU/T.