Localized surface plasmon resonance sensor for magnetic field detection

We report a localized surface plasmon resonance (LSPR) sensor that consists of noble metal and ferromagnetic material. This hybrid system offers tunable LSPR frequencies by the refractive index change of the surrounding medium as well as the external magnetic field around the nanostructures. We used a gold nanoparticle with Co and Fe. The thin ferromagnetic layers coated on gold nanoparticles have a linear dependence between relative permittivity with an applied magnetic field. The underlying mechanism is the change of the dielectric constant of the ferromagnetic film when it has aligned magnetization in the same direction of the external magnetic field. Consequently, change of the LSPR absorption spectrum of the hybrid nanostructures.