The sensitivity of a biosensor is one of the most important parameters that determine its performance. It depends on many factors, such as excitation wavelength of incident optical radiation (λ), composition, type, and thickness of the ferromagnetic Co layer (tCo), plasmonic Au, and high refractory metal, Ti, involved, and sensing/excitation configuration. In this paper, both the surface plasmon resonance (SPR at the magnetic field, H = 0) and magneto-optic SPR (MOSPR at H) sensitivity of the sensors have been theoretically calculated in the visible wavelength regime using air-helium media as probing samples in the Kretschmann configuration, and their performances are compared side by side.

The calculated MOSPR sensitivity is almost 12.5× larger as compared to the SPR sensitivity for the same geometry, excitation condition, and probing media λ = 632.8 nm. Likewise, the MOSPR sensitivity is almost 10× larger as compared to the MOSPR sensitivity at λ = 515 nm for the same geometry and probing media. On decreasing the Co layer thickness, the sensitivity of the MOSPR sensor is further increased by almost 3 times. The sensitivity can be further improved by additional optimization of the material used and sensor configuration employed for detection.