Surface plasmon polariton ͑SPP͒ excitation effects on the magneto-optical ͑MO͒ activity of Au capped Ag/Co/Ag trilayers are studied as a function of Co thickness. An enhancement of the transverse MO Kerr signal under SPP excitation as compared with that obtained without SPP excitation is measured with a maximum value of 150 times obtained for the trilayer with 8 nm Co. Such enhancement on the magneto-optical activity due to SPP excitation is also five times higher than that obtained in Au/Co/Au trilayers in similar conditions. The lower optical absorption in the studied range and the sharper plasmon resonance of Ag vs Au are responsible for these values. On the other hand, magnetic field-induced SPP wavevector modulation ͑⌬k / k͒ SPP is studied for these trilayers and compared both with previous results in the Au/Co/Au system as well as with the theory. In the wavelength considered here, the obtained values are similar for both Ag-and Au-based structures and on the order of 10 −4 , pinpointing the role of the magnetic layer on the SPP wavevector modulation.

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In this work, nanostructured ZnCo 2 O 4 was synthesized via a microwave-assisted colloidal method, and its application as gas sensor for the detection of CO was studied. Typical diffraction peaks corresponding to the cubic ZnCo 2 O 4 spinel structure were identified at calcination temperature of 500°C by X-ray powder diffraction. A high degree of porosity in the surface of the nanostructured powder of ZnCo 2 O 4 was observed by scanning electron microscopy and transmission electron microscopy, faceted nanoparticles with a pockmarked structure were clearly identified. The estimated average particle size was approximately 75 nm. The formation of ZnCo 2 O 4 material was also confirmed by Raman characterization. Pellets fabricated with nanostructured powder of ZnCo 2 O 4 were tested as sensors using CO gas at different concentrations and temperatures. A high sensitivity value of 305-300 ppm of CO was measured at 300°C, indicating that nanostructured ZnCo 2 O 4 had a high performance in the detection of CO.

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