Enhanced Magneto-Optical Kerr Effect-Based Multilayers/Pd for Hydrogen Magnetoplasmonic Transducers

We studied magneto-optical surface plasmon resonance (MOSPR) theoretically and experimentally to design a hydrogen gas sensor. A prism-based MOSPR design was used to test the sensor’s reflectance and perform related measurements. Results showed that the ferromagnetic materials Co, Fe, and Ni can improve the sensor’s gas-sensing performance. In addition, the MOSPR of Au or Ag base-ferromagnetic material coated with 1, 2, or 3 nm-thick Pd layers was studied in air and hydrogen environments. A thick Pd layer increases response time in contrast to a thin Pd layer. Moreover, ferromagnetic materials considerably affect theta shift hydrogen sensing, reaching a maximum Kerr effect of > 1.5. Among ferromagnetic materials, Fe exhibits the best performance. Its reflectance at air and hydrogen resonance angles are 0.013089 and 0.0083943, respectively. The maximum angle shift between hydrogen gas and Fe ferromagnetic materials’ air is 0.294° when the Pd layer is 3 nm thick. This finding suggests that the sensitivity of a hydrogen gas sensor can be improved by defining the theta shift based on a specific ferromagnetic material and Pd thickness.