Achieving high figure-of-merit (defined as the ratio between refractive index sensitivity and spectral line width) in surface plasmon sensors is a fundamental quest for ultrasensitive chemical and biomedical sensing applications. Due to ohmic loss of plasmonic metal thin films, the theoretical limit of figure-of-merit is around 54 RIU–1 (refractive index unit) for Au-based plasmonic sensors at 650 nm wavelength. Here, we report a way to significantly boost the device figure-of-merit by incorporating low loss magneto-optical oxides in a novel metal–insulator–metal magnetoplasmonic sensor. Our theoretical analysis shows that a record high figure-of-merit of 39600 RIU–1 can be achieved in a simple multilayer thin film sensor device at the wavelength of 650 nm, which well exceeds that of conventional surface plasmon resonance sensors at the same wavelength. A high figure-of-merit of 964 ± 150 RIU–1 is demonstrated experimentally at 650 nm, 17.8× higher than the theoretical limit of Au surface plasmon resonance sensors at the same wavelength. The high figure-of-merit originates from strong coupling between the magneto-optical waveguide mode and the surface plasmon resonance mode causing a narrow transverse magneto-optical Kerr effect spectrum with Fano line shape at resonant excitation conditions. The limit-of-detection reaches 4.13 × 10–6 RIU, which is 16× higher compared to a standard Au SPR sensor measured on the same setup. Biomedical sensing using bovine serum albumin solutions and biotin–streptavidin interaction demonstrate excellent sensing performance and chemical stability of such metal–insulator–metal magnetoplasmonic sensors.Keywords: biosensor; magnetoplasmonic; metal−insulator−metal; transverse magneto-optical Kerr effect;

Following intense research on two-dimensional (2D) materials, there has been a resurgence of interest in 2D layered hybrid organic–inorganic perovskites. These 2D perovskites have direct band gaps regardless of their thickness. Excitons are confined to monolayers because of the materials' self-organized quantum-well electronic structure. Gaining insight into the exciton dynamics is central to understanding the light–matter interactions in 2D organic–inorganic perovskites. Herein, we investigate the free-exciton dynamics in 2D layered CH3(CH2)3NH3PbI4 perovskite, demonstrating an anomalous temperature variation of the photoluminescence (PL) energy, which deviates from the conventional Varshni formula and is consistent with the behaviour of Bose–Einstein oscillators. The acoustic phonons induced by the coherent lattice motion of the atoms result in a positive temperature variation. Two-pulse emission modulation measurements reveal the excitation mechanism of the strong two-photon PL in CH3(CH2)3NH3PbI4 perovskite, in which two photons are simultaneously absorbed through a virtual state.

•Pd/SnO2/SiO2/Si heterojunctions were produced using magnetron sputtering method.•The heterojunctions show a high response (∼17363%) to 1% H2 in air.•The interfacial energy band characteristics of Pd/SnO2/SiO2/Si heterojunctions are proposed.A series of Pd/SnO2/SiO2/Si heterojunction sensors were produced using magnetron sputtering method. It is found that the Pd/SnO2/SiO2/Si heterojunction exhibits ultrahigh H2 response of ∼17363% to 1.0% H2 at room temperature, and has fast response and recovery, excellent stability and selectivity. Therefore, this kind of heterojunction may be a promising candidate for effective H2 detection at room temperature. The H2 response characteristics and the optimum operating voltage of the sensors is modulated by the interface barrier potential between SnO2 and Si, which can be understood by the interfacial energy band characteristics of the Pd/SnO2/SiO2/Si heterojunction.The Pd/SnO2/SiO2/Si heterojunction exhibits ultrahigh response of ∼17363% to 1.0% H2, excellent stability and selectivity at room temperature.

•NiO/V2O5 hybrid electrochromic film has been prepared.•The hybrid film was obtained with nanoflake-like NiO film as substrate.•The hybrid film has a nanoporous structure.•The hybrid film has good electrochromic properties.Nanoporous NiO/V2O5 hybrid film has been successfully prepared by combining chemical bath deposition (CBD) and electrochemical deposition methods. The electrochemical and optical properties of the hybrid film were investigated by cyclic voltammetry (CV), amperometric i–t, UV–vis spectroscopy and colorimetry analysis. Compared with single V2O5 electrochromic film, the NiO/V2O5 hybrid electrochromic film reveals reasonably good cyclic stability, better transmittance modulation (35% at 776 nm) and higher coloration efficiency (30.6 C−1 cm2 at 776 nm). The noticeably improved electrochromic properties are mainly attributed to the introduction of NiO polycrystal substrate with nanoflake-like structure, which helps strengthen the structural stability of V2O5 film and improve the performance of Li+ ions intercalation/deintercalation.

•Polyaniline and TiO2 nanorods array hybrid electrochromic film was obtained.•Electrochromic properties of the hybrid film were studied.•The hybrid film has the loose and porous surface.•The hybrid film could exhibit three different colors.Titanium dioxide (TiO2) nanorods (NRs) array was successfully prepared via hydrothermal method on fluorine doped tinoxide (FTO) coated transparent conductive glass substrate. The hybrid film of polyaniline (PANI)/TiO2 NRs was achieved through electrochemical polymerization of aniline onto the TiO2 NRs array film. The electrochromic and optical properties of the hybrid film were investigated by cyclic voltammetry (CV), amperometric i–t and UV–vis spectroscopy. The results indicate that the hybrid film has long term stability and reversible color changes after cyclic voltammetry scans for 200 circles. The PANI/TiO2 NRs hybrid film can show three different colors. Response time of PANI/TiO2 NRs hybrid film is about 0.7 s and 2.6 s at different states, respectively. The TiO2 NRs array and the loose, porous surface among the hybrid film facilitate charge transmission and also provide large surface area for electrochemical reaction.

•A novel carbazole-triphenylamine-based electrochromic film has been prepared.•The film could exhibit different colors as bluish green, light yellow and off-white.•The film can sensitively change its color within seconds.•The biggest different average emissivity dynamic of the film is 0.082.4,4′-Di(N-carbazolyl)triphenylamine (DCBZ-TPA) is synthesized and its polymer film was deposited on ITO-glass through electrochemical polymerization. Electrochromic properties of the novel film were investigated by cyclic voltammetry and amperometric i–t curve. The optical properties of the film were investigated by UV–vis and FT-IR spectroscopy. The electrochromic film can sensitively change its color within seconds, which can be described as bluish green, light yellow and off-white. A biggest different average emissivity dynamic of the film is 0.082 in the wavelength of 8–14 μm.

•Ce1.5Y1.5Fe5O12 film was successfully deposited on silicon substrates.•The θF of Ce1.5Y1.5Fe5O12 film reaches −6410 deg/cm at 1550 nm wavelength.•MO spectra and optical constants of this film have been characterized.•The oxygen partial pressure is found to significantly influence the Ce solubility.Polycrystalline Ce:YIG thin films deposited on silicon are promising material candidates for integrated nonreciprocal photonic devices. So far, the reported Faraday rotation of polycrystalline Ce:YIG thin films on silicon is much lower than that of their single crystal or epitaxial thin film counterparts, limiting the magneto-optical figure of merit, device bandwidth and fabrication tolerance. In this paper, we report the growth of Ce:YIG thin films on silicon from targets with high Ce concentration up to nominally Y1.5Ce1.5Fe5O12 by pulsed laser deposition. The polycrystalline Y1.5Ce1.5Fe5O12 thin film showed pure garnet phase, smooth surface roughness of 0.7 nm, a dominant Ce3+ valence state and a bulk-like saturation magnetization of 125 emu/cm3 at room temperature. This material shows high Faraday rotation of −6410 deg/cm at 1550 nm wavelength, exceeding that of an Y2Ce1Fe5O12 epitaxial thin film on a GGG (100) substrate. However higher loss and lower figure of merit is also observed at 1550 nm wavelength compared to Y2Ce1Fe5O12 thin films, possibly due to the low oxygen partial pressure during fabrication. Low deposition oxygen partial pressure is essential to enhance the Ce solubility and Ce3+ concentration, which results in large Faraday rotation.