N-doped ZnO thin film for development of magnetic field sensor based on surface plasmon resonance.

Magnetic-field-dependent optical properties of nitrogen-doped ZnO (ZnO:N) thin films were investigated using surface plasmon resonance (SPR) and a highly sensitive (4.65/Tesla) magnetic field sensor has been realized. The refractive index (RI) of ZnO:N film increases from 1.949 to 2.025 with increase in N doping from 0% to 10% demonstrating tunable RI. In contrast to pure ZnO, SPR curves for ZnO:N films exhibit a shift toward lower angles with increasing applied magnetic field from 0 to 35 mT due to change in reflectance of light upon reflection from ferromagnetic surface. Results indicate promising application of ferromagnetic ZnO:N film as a magnetic field sensor.