Ultra-thin magnetic dielectric films are of prime importance due to their applications for nanophotonics and spintronics. Here we propose an efficient method for the magneto-optical investigation of ultra-thin magnetic films that allows one to access their state of magnetization and magneto-optical properties. It is based on the surface-plasmon-polariton-assisted transverse magneto-optical Kerr effect (TMOKE). In our experiments sub-100nm-thick bismuth-substituted lutetium iron-garnet films covered with a plasmonic gold grating have been analyzed. The excitation of surface plasmon-polaritons provides resonance enhancement of TMOKE up to 0.04 and makes it easily detectable in experiment. For films thicker than 40 nm the TMOKE marginally depends on the film thickness. Further decrease of the film thickness diminishes TMOKE since for such thicknesses the surface plasmon-polariton field partly penetrates inside the nonmagnetic substrate. Nevertheless, the TMOKE remains measurable even for few-nm-thick films, which makes this technique unique for the magneto-optical study of ultra-thin films. Particularly, the proposed method reveals that the off-diagonal components of the magnetic film permittivity tensor grow slightly with the reduction of the film thickness.Currently, ultra-thin ferrimagnetic dielectric films are of significant interest due to their applications in nanophotonics, magnonics and spintronics [1][2][3][4][5][6]. Magnetic dielectrics like bismuthsubstituted iron-garnets have outstanding optical properties in the near infrared where they evince low optical absorption and a relatively large magneto-optical response [7][8][9][10]. Practical use of spintronic devices for magnetic information recording requires magnetic field confinement in the

We report on a magneto-photonic crystal on-chip optical sensor for specific analyte detection with polypyrrole and gold nano particles as modified photonic crystal waveguide cover layers. The reaction of the active sensor material with various analytes modifies the electronic structure of the sensor layer causing changes in its refractive index and a strong transduction signal. Magneto-photonic crystal enhanced polarization rotation sensitive to the nature of the cover layer detects the index modification upon analyte adsorption. A high degree of selectivity and sensitivity are observed for aqueous ammonia and methanol with polypyrrole and for thiolated-gold-with gold-nanoparticles covers.

Articles you may be interested inPlasmon resonance enhancement of Faraday rotation of liquid phase epitaxy grown garnet films populated with gold nanoparticles on the film surfaces Growth effects (rotation rate) on the characteristics of bismuth substituted lutetium iron garnets Significant departures from bulk-like magneto-optic behavior are found in ultra-thin bismuth-substituted iron-garnet films grown by liquid-phase-epitaxy. These changes are due, at least in part, to geometrical factors and not to departures from bulk-composition in the transient layer at the filmsubstrate interface. A monotonic increase in specific Faraday rotation with reduced thickness is the signature feature of the observed phenomena. These are traced to size-dependent modifications in the diamagnetic transition processes responsible for the Faraday rotation. These processes correspond to the electronic transitions from singlet 6 S ground states to spin-orbit split excited states of the Fe 3þ ions in the garnet. A measurable reduction in the corresponding ferrimagnetic resonance linewidths is found, thus pointing to an increase in electronic relaxation times and longer lived excitations at reduced thicknesses. These changes together with a shift in vibrational frequency of the Bi-O bonds in the garnet at reduced thicknesses result in greatly enhanced magneto-optical performance. These studies were conducted on epitaxial monocrystalline Bi 0.8 Gd 0.2 Lu 2 Fe 5 O 12 films. V C 2015 AIP Publishing LLC. [http://dx.