Fig. 1. Schematic view of the Au/FexCo1−x MOSPR sensor in a Kretschmann prism coupling system. The external magnetic field is applied along the y axis and perpendicular to the incident plane.

Fig. 2. (a) XRD figures of different component FexCo1−x samples with about 18 nm thickness. (b) Reflectivity versus incidence angle for the Au(18  nm)/Fe/Co/Fe0.7Co0.3(18  nm) device; the inset shows the simulated result (dashed line) compared to the experimental curve (solid line) of Au(18  nm)/Fe0.7Co0.3(18  nm). The reflectivity spectra are measured in air.

Fig. 3. (a) Room temperature LMOKE hysteresis of FexCo1−x thin films measured under an incident laser wavelength of 650 nm. (b) The LMOKE Kerr rotation and Kerr ellipticity of FexCo1−x thin films with different composition x.

Fig. 4. (a) Simulated device sensitivity as a function of Au and Co layer thicknesses in the Au/Co transducer. (b) The optimum sensitivity of Au/FexCo1−x MOSPR transducers with different composition x; the error bar of sensitivity is determined by the error bar of ϵxz′ and ϵxz′′ as shown in Table 1.

Fig. 5. (a) Experimental and simulated angular spectrum of R for p-polarized incident light in three Au/FexCo1−x MOSPR transducers measured in water (n=1.332) (b) Experimental and simulated angular spectrum of R(+H)−R(−H) for p-polarized incident light in three Au/Fe0.7Co0.3 MOSPR transducers. (c) Experimental angular spectrum of R(+H)−R(−H) as a function of the index of the sensing medium for the Au/Fe0.7Co0.3 transducer. (d) Comparison of the index sensitivity for Au/Fe, Au/Fe0.7Co0.3 and Au/Co devices as a function of the index of the sensing medium.