Search Results (150)

The photonic spin Hall effect (PSHE) has emerged as a powerful metrological approach for precision measurements. Dynamic manipulation of PSHE through external stimuli could substantially expand its applications. In this work, we present a simple and active modulation scheme for PSHE in a surface plasmon resonance (SPR) structure by exploiting electric-field-tunable refractive indices of electro-optic materials. By applying an electric field, the enhancement of PSHE spin shifts is observed, and the dual-field control can further amplify these spin shifts through synergistic effects in this SPR structure. Notably, various operation modes of external electric field enable the real-time switching between two high-performance sensing functionalities (refractive index detection and angle measurement). Therefore, our designed PSHE sensor based on SPR structure with a simple structure of only three layers not only makes up for the complex structure in multi-functional sensors, but more importantly, this platform establishes a new paradigm for dynamic PSHE manipulation while paving the way for advanced multi-functional optical sensing technology. Full article

Cerium-doped zinc cobaltite spinel thin films, $\mathrm{Z}\mathrm{n}{\mathrm{C}\mathrm{e}}_{\mathrm{x}}{\mathrm{C}\mathrm{o}}_{2-\mathrm{x}}{\mathrm{O}}_4 (0.00\le \mathrm{x}\le 0.05)$, were synthesized via spray pyrolysis, and their structural, morphological, optical, and electrical properties were analyzed. X-ray diffraction (XRD) confirmed a cubic spinel structure with a predominant (311) orientation across all compositions. Raman spectroscopy further verified this phase, revealing four active vibrational modes at 180 cm⁻¹, 470 cm⁻¹, 515 cm⁻¹, and 682 cm⁻¹. Scanning electron microscopy (SEM) indicated a uniform grain distribution, while energy-dispersive X-ray spectroscopy (EDS) confirmed the presence of Ce, Zn, Co, and O. Optical measurements revealed two distinct bandgaps, decreasing from 2.32 eV to 2.20 eV for the lower-energy transition and from 3.38 eV to 3.18 eV for the higher-energy transition. Hall effect measurements confirmed p-type conductivity in all films. Electrical analysis showed a reduction in resistivity, from 280.3 Ω·cm to 15.4 Ω·cm, along with an increase in carrier concentration from 1.15 × 10¹⁶ cm⁻³ to 8.15 × 10¹⁷ cm⁻³ with higher Ce content. These results demonstrate that spray pyrolysis is a cost-effective and scalable method for producing Ce-doped ZnCo₂O₄ thin films with tunable properties, making them suitable for electronic and optoelectronic applications. Full article

Sensor arrays are arrangements of sensors that follow a certain pattern, usually in a row–column distribution. This study presents a systematic review on sensor arrays. For this purpose, several systematic searches of recent studies covering a period of 10 years were performed. As a result of these searches, 361 papers have been analyzed in detail. The most relevant aspects for sensor array design have been studied. In relation to sensing technologies, different categories were identified: resistive/piezoresistive, capacitive, inductive, diode-based, transistor-based, triboelectric, fiber optic, Hall effect-based, piezoelectric, and bioimpedance-based. Other aspects of sensor array design have also been analyzed: applications, validation experiments, software used for sensor array data analysis, sensor array characteristics, and performance metrics. For each aspect, the studies were classified into different subcategories. As a result of this analysis, different emerging technologies and future research challenges in sensor arrays were identified. Full article

The photon spin Hall effect (PSHE) arises from the spin–orbit interaction of light. Metasurfaces enable precise control over the PSHE through their influence. Using electromagnetic simulations as its foundation, this work engineers a metal–insulator–metal (MIM) metasurface for generating vortex beams in the near-infrared band, targeting enhanced modulation of the PSHE. Electromagnetic simulations embed vanadium dioxide (VO₂)—a thermally responsive phase-change material—within the MIM metasurface architecture. Numerical evidence confirms that harnessing VO₂’s insulator–metal-transition-mediated optical switching dynamically tailors spin-dependent splitting in the illuminated MIM-VO₂ hybrid, thereby achieving a significant amplification of the PSHE displacement. Electromagnetic simulations determine the reflection coefficients for both VO₂ phase states in the MIM-VO₂ structure. Computed spin displacements under vortex beam incidence reveal that VO₂’s phase transition couples to the MIM’s top metal and dielectric layers, modifying reflection coefficients and producing phase-dependent PSHE displacements. The simulation results show that the displacement change of the PSHE before and after the phase transition of VO₂ reaches 954.7 µm, achieving a significant improvement compared with the traditional layered structure. The dynamic modulation mechanism of the PSHE based on the thermal–optical effect has been successfully verified. Full article

Recent achievements in ultrafast spin physics have enabled the use of heterostructures composed of ferromagnetic (FM)/non-magnetic (NM) thin layers for terahertz (THz) generation. The mechanism of THz emission from FM/NM multilayers has been typically ascribed to the inverse spin Hall effect (ISHE). In this work, we probe the mechanism of the ISHE by inserting a second ferromagnetic layer in the form of an alloy between the FM/NM system. In particular, by utilizing the co-sputtering technique, we fabricate Fe/L1₀-FePt/Pt ultra-thin heterostructures. We successfully grow the tetragonal phase of FePt (L1₀-phase) as revealed by X-ray diffraction and reflection techniques. We show the strong magnetic coupling between Fe and L1₀-FePt using magneto-optical and Superconducting Quantum Interference Device (SQUID) magnetometry. Subsequently, by utilizing THz time domain spectroscopy technique, we record the THz emission and thus we the reveal the efficiency of spin-to-charge conversion in Fe/L1₀-FePt/Pt. We establish that Fe/L1₀-FePt/Pt configuration is significantly superior to the Fe/Pt bilayer structure, regarding THz emission amplitude. The unique trilayer structure opens new perspectives in terms of material choices for the future spintronic THz sources. Full article

This study examines the microstructural evolution, mechanical properties, and wear behavior of medium-carbon dual-phase steel (AISI 1040) processed via Multi-Axis Compression (MAC). The DP steel was produced through inter-critical annealing at 745 °C, followed by MAC at 500 °C, resulting in a refined grain microstructure. Optical micrographs confirmed the presence of ferrite and martensite phases after annealing, with significant grain refinement observed following MAC. The average grain size decreased from 66 ± 4 μm to 18 ± 1 μm after nine MAC passes. Mechanical testing revealed substantial improvements in hardness (from 145 ± 9 HV to 298 ± 18 HV) and ultimate tensile strength (from 557 ± 33 MPa to 738 ± 44 MPa), attributed to strain hardening and the Hall–Petch effect. Fractographic analysis revealed a ductile failure mode in the annealed sample, while DP0 and DP9 exhibited a mixed fracture mode. Both DP0 and DP9 samples demonstrated superior wear resistance compared to the annealed sample. However, the DP9 sample exhibited slightly lower wear resistance than DP0, likely due to the fragmentation of martensite induced by high accumulated strain, which could act as crack initiation sites during sliding wear. Furthermore, wear resistance was significantly enhanced due to the combined effects of the DP structure and Severe Plastic Deformation (SPD). These findings highlight the potential of MAC processing for developing high-performance steels suitable for lightweight automotive applications. Full article

Tantalum oxide is a wide bandgap material commonly used as an insulating dielectric layer for devices. In this work, hexagonal Ta₂O₅ (δ-Ta₂O₅) films doped with tungsten (W) were deposited on α-Al₂O₃ (0001) by metal–organic chemical vapor deposition (MOCVD). The effects of W doping on the structural, morphology, and photoelectrical properties of the obtained films were studied. The results showed that all W-doped films were n-type semiconductors. The XRD measurement result exhibited that the increase in the W doping concentration leads to the changes in the preferred growth crystal plane of the films from δ-Ta₂O₅ ($10\overline{1}1$) to (0001). The 1.5% W-doped film possessed the best crystal quality and conductivity. The Hall measurement showed that the minimum resistivity of the film was 2.68 × 10⁴ Ω∙cm, and the maximum carrier concentration was 7.39 × 10¹⁴ cm³. With the increase in the W concentration, the surface roughness of the film increases, while the optical bandgap decreases. The optical band gap of the 1.5% W-doped film was 3.92 eV. The W doping mechanisms were discussed. Full article

The tin dioxide (SnO₂) thin films in this work were prepared by using plasma-enhanced atomic layer deposition (PEALD), and a systematic analysis was conducted to evaluate the influence of post-deposition annealing at various temperatures in a nitrogen–hydrogen mixed atmosphere on their surface morphology, optical behavior, and electrical performance. The SnO₂ films were characterized by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Hall effect measurements. With increasing annealing temperatures, the SnO₂ films exhibited enhanced crystallinity, a higher oxygen vacancy (O_V) peak area ratio, and improved mobility and carrier concentration. These enhancements make the annealed SnO₂ films highly suitable as electron transport layers (ETLs) in perovskite solar cells (PSCs), providing practical guidance for the design of high-performance PSCs. Full article

Topological photonic crystals have garnered significant attention due to their fascinating topological edge states. These states are robust against sharp bends and defects and exhibit the novel property of unidirectional transmission. In this study, we analyze the topological edge states of gyromagnetic topological photonic crystals in analogy with the quantum Hall effect. Through expanding and shrinking six dielectric cylinders, the optical quantum spin Hall effect is achieved. And helical edge states with pseudo-spin are demonstrated. Owing to the novel topological properties of these edge states, robust waveguides are proposed. Furthermore, integrating these two distinct types of topological states, a novel circulator with topological characteristics is designed. These topologically protected photonic devices will be beneficial for developing integrated circuits. Full article

The Al-Sb co-doped SnO₂ composite thin films were prepared by the sol–gel spin-coating method. The structure, morphology, optical and electrical properties of the samples were investigated using XRD, XPS, SEM, UV-Vis spectroscopy, and Hall effect tester, respectively. It was found that when the aluminum doping amount was 15 at%, the resistivity of the sample was the lowest, and the overall optoelectronic performance was the best. Moreover, the Al-SnO₂ composite thin film transformed from an n-type semiconductor to a p-type semiconductor. When Al and Sb were co-doped, the carrier concentration increased significantly from 4.234 × 10¹⁹ to 6.455 × 10²⁰. Finally, the conduction type of the Al-Sb-SnO₂ composite thin film changed from p-type to n-type. In terms of optical performance, the transmittance of the Al-Sb co-doped SnO₂ composite thin films in the visible light region was significantly improved, reaching up to 80% on average, which is favorable for applications in transparent optoelectronic devices. Additionally, the absorption edge of the thin films exhibited a blue-shift after co-doping, indicating an increase in the bandgap energy, which can be exploited to tune the light-absorption properties of the thin films for specific photonic applications. Full article

Thulium iron garnet (Tm₃Fe₅O₁₂, TmIG) is a promising material for next-generation spintronic and quantum technologies owing to its high Curie temperature and strong perpendicular magnetic anisotropy. However, conventional magnetometry techniques are limited by insufficient spatial resolution and sensitivity to probe local magnetic phase transitions and critical spin dynamics in thin films. In this study, we present the first quantitative investigation of local magnetic field fluctuations near the Curie temperature in TmIG thin films using nitrogen-vacancy (NV) center-based quantum sensing. By integrating optically detected magnetic resonance (ODMR) and NV spin relaxometry (T₁ measurements) with macroscopic techniques such as SQUID magnetometry and Hall effect measurements, we systematically characterize both the static magnetization and dynamic spin fluctuations across the magnetic phase transition. Our results reveal a pronounced enhancement in NV spin relaxation rates near 360 K, providing direct evidence of critical spin fluctuations at the nanoscale. This work highlights the unique advantages of NV quantum sensors for investigating dynamic critical phenomena in complex magnetic systems and establishes a versatile, multimodal framework for studying local phase transition kinetics in high-temperature magnetic insulators. Full article

As the typical representative of amorphous oxide semiconductors (AOS), quaternary indium gallium zinc oxide (IGZO) has been applied as the active layer of thin-film transistors (TFTs), but their mobility is still low (usually ~10 cm²/Vs). IGTO is reported to have larger mobility owing to the addition of Tin (Sn) in IZO. So, whether Sn doping can increase the optoelectronic properties of IGZO is a new topic worth studying. In this study, four series of quinary InGaZnSnO (IGZTO) oxide thin films were deposited on glass substrates using a high-purity IGZTO (In:Ga:Zn:Sn:O = 1:0.5:1.5:0.25:x, atomic ratio) ceramic target by RF magnetron sputtering. The effects of fabrication parameters (sputtering power, argon gas flow, and target-to-substrate distance) and film thickness on the microstructure, optical, and electrical properties of IGZTO thin films were investigated. The results show that all IGZTO thin films deposited at room temperature (RT) are amorphous and have a smooth and uniform surface with a low roughness (RMS of 0.441 nm, RA of 0.332 nm). They exhibit good average visible light transmittance (89.02~90.69%) and an optical bandgap of 3.47~3.56 eV. When the sputtering power is 90 W, the argon gas flow rate is 50 sccm, and the target-to-substrate distance is 60 mm, the IGZTO films demonstrate optimal electrical properties: carrier concentration (3.66 × 10¹⁹ cm⁻³), Hall mobility (29.91 cm²/Vs), and resistivity (0.54 × 10⁻² Ω·cm). These results provide a valuable reference for the property modulation of IGZTO films and the potential application in optoelectronic devices such as TFTs. Full article

Two-dimensional (2D) Xenes, including graphene where X represents C, Si, Ge, and Te, represent a groundbreaking class of materials renowned for their extraordinary electrical transport properties, robust photoresponse, and Quantum Spin Hall effects. With the growing interest in 2D materials, research on germanene-based systems remains relatively underexplored despite their potential for tailored optoelectronic functionalities. Herein, we demonstrate a facile and rapid chemical synthesis of tellurium-doped germanene hydride (Te-GeH) nanostructures (NSs), achieving precise atomic-scale control. The 2D Te-GeH NSs exhibit a broadband optical absorption spanning ultraviolet (UV) to visible light (VIS), which is a critical feature for multifunctional photodetection. Leveraging this property, we engineer photoelectrochemical (PEC) photodetectors via a simple drop-casting technique. The devices deliver excellent performance, including a high responsivity of 708.5 µA/W, ultrafast response speeds (92 ms rise, 526 ms decay), and a wide operational bandwidth. Remarkably, the detectors operate efficiently at zero-bias voltage, outperforming most existing 2D-material-based PEC systems, and function as self-powered broadband photodetectors. This work not only advances the understanding of germanene derivatives but also unlocks their potential for next-generation optoelectronics, such as energy-efficient sensors and adaptive optical networks. Full article

The study explores the optical and transport properties of polycrystalline ZnO thin films prepared using reactive pulsed mid-frequency sputtering with RF electron cyclotron wave resonance (ECWR) plasma. This deposition method increases the ionization degree of sputtered particles, the dissociation of reactive gas and the plasma density of pulsed reactive magnetron plasma. Optical absorption spectra reveal a sharp Urbach edge, indicating low valence band disorder. Lattice disorder and deep defect concentration are more likely to occur in samples with higher roughness. PL analysis at low temperature reveals in all samples a relatively slow (μs) red emission band related to deep bulk defects. The fast (sub-ns), surface-related blue PL band was observed in some samples. Blue PL disappeared after annealing in air at 500 °C. Room temperature Hall effect measurements confirm n-type conductivity, though with relatively low mobility, suggesting defect-related scattering. Persistent photoconductivity was observed under UV illumination, indicating deep trap states affecting charge transport. These results highlight the impact of deposition and post-treatment on polycrystalline ZnO thin films, offering insights into optimizing their performance for optoelectronic applications, such as UV detectors and transparent conductive oxides. Full article

Yb_xEr_yZnO thin films with a low concentration (x = 5%, y = 0, 1, 3%) were made on glass substrates using the spray pyrolysis method. The films were characterized through the use of specific techniques to investigate their structural, optical, and electrical properties. The XRD structural analysis of the films revealed that they are polycrystalline with a hexagonal wurtzite structure and a preferential orientation in the (002) direction. The optical characterization of the co-doped layers in the range of 200 to 800 nm revealed that co-doping had a significant impact on the values of transmission. A well-defined peak in the infrared domain centered around 980 nm was observed in photoluminescence measurements. This peak signifies the transition between the electronic levels ²F_5/2 (ground state) and ²F_7/2 (excited state), proving that photons are efficiently transferred between the ZnO matrix and the Yb³⁺ ion. All layers exhibited n-type conduction and an electrical resistivity decrease to 6.0 × 10⁻² Ω cm according to Hall effect measurements at room temperature. Full article