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Transmission-Line Model for Materials with Spin-Momentum Locking
摘要： We provide a transmission-line representation for channels exhibiting spin-momentum locking (SML) that can be used for both time-dependent and steady-state transport analysis on a wide variety of materials with spin-orbit coupling such as topological insulators, Kondo insulators, transition metals, semimetals, oxide interfaces, and narrow band-gap semiconductors. This model is based on a time-dependent four-component di?usion equation obtained from the Boltzmann transport equation assuming linear response and elastic scattering in the channel. We classify all electronic states in the channel into four groups (U+, D+, U?, and D?) depending on the spin index [up (U), down (D)] and the sign of the x component of the group velocity (+, ?) and assign an average electrochemical potential to each of the four groups to obtain the four-component di?usion equation. For normal metal channels, the model decouples into the well-known transmission-line model for charge and a time-dependent version of the Valet-Fert equation for spin. We ?rst show that, in the steady-state limit, our model leads to simple expressions for charge-spin interconversion in SML channels in good agreement with existing experimental data on diverse materials. We then use the full time-dependent model to study spin-charge separation in the presence of SML, a subject that has been controversial in the past. Our model shows that the charge and spin signals travel with two distinct velocities, resulting in well-known spin-charge separation, which is expected to persist even in the presence of SML. However, our model predicts that the lower velocity signal is purely spin, while the higher velocity signal is largely charge with an additional spin component proportional to the degree of SML, which has not been noted before. Finally, we note that our model can be used within standard circuit simulators such as SPICE to obtain numerical results for complex geometries.
关键词： spin-orbit coupling,spin-charge separation,transmission-line model,topological insulators,charge-spin interconversion,spin-momentum locking
更新于2025-09-23 15:21:01
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Contents: (Adv. Funct. Mater. 44/2018)
摘要： Silica nanofibrous membranes produced by direct electrospinning of a sol-gel solution without a sacrificing polymer allow high-end separation and purification due to a high thermal and chemical resistance. The water repellent or absorbing nature can be tuned by applying a humidity or thermal treatment. It is showcased that fast gravity driven membrane separation of heterogeneous azeotropes can be achieved.
关键词： thermal resistance,chemical resistance,sol-gel,electrospinning,azeotrope separation,silica nanofibrous membranes
更新于2025-09-23 15:21:01
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[IEEE 2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE) - Nara (2018.9.11-2018.9.14)] 2018 57th Annual Conference of the Society of Instrument and Control Engineers of Japan (SICE) - Evaluation of Molecular Structure in Each Processing Step of Cashmere Fibers Based on IR Spectroscopy
摘要： In this paper, we propose a molecular structure in each processing step of cashmere fibers that by using an IR spectroscopy. When manufacturing cashmere fiber products, hand touch quality and strength often decrease. In order to clarify the cause, cashmere fibers of each process were obtained from Mongolia. Absorption spectra of cashmere fiber can be measured by ATR method in IR spectroscopy. In the washing process, no change in molecular structure was shown and only wool grease was removed. The measured spectra were waveform separated and the molecular structure of the cashmere fiber was analyzed. In the cashmere fibers of each (cid:48)(cid:49)(cid:47)(cid:37)(cid:39)(cid:50)(cid:50)(cid:1)(cid:50)(cid:51)(cid:39)(cid:48)(cid:3)(cid:1)(cid:51)(cid:42)(cid:39)(cid:49)(cid:39)(cid:1)(cid:54)(cid:35)(cid:50)(cid:1)(cid:46)(cid:47)(cid:1)(cid:37)(cid:42)(cid:35)(cid:46)(cid:41)(cid:39)(cid:1)(cid:43)(cid:46)(cid:1)(cid:62)(cid:1)(cid:42)(cid:39)(cid:44)(cid:43)(cid:55)(cid:1)(cid:35)(cid:46)(cid:38)(cid:1)(cid:63)(cid:1) sheet of the secondary structure of the protein. The cashmere fibers in the bleaching and decoloring process steps showed an increase in cysteic acid by the oxidation-reduction reaction. Therefore, the cause of the decline in the quality of cashmere fiber products was chemical treatment in bleaching and decoloring process. This result is applied as a quality evaluation method in the manufacturing process of cashmere textile products.
关键词： Absorption spectrum,IR spectroscopy,Molecular structure,Cashmere fiber,Waveform separation
更新于2025-09-23 15:21:01
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Using Nonionic Surfactants for Production of Semiconductor-Type Carbon Nanotubes by Gel-Based Affinity Chromatography
摘要： Single-wall carbon nanotubes (SWCNTs) have remarkable properties based on their electronic properties, i.e., metallic or semiconducting types, but as-grown SWCNTs contain a mixture of both types. Presented here is an improved and detailed method for producing highly enriched semiconducting SWCNTs from a colloidal suspension of as-grown SWCNTs through agarose gel column-based affinity chromatography. After a 2 wt% sodium dodecyl sulphate (SDS) aqueous dispersion of SWCNTs is passed through the gel column, metal-type SWCNTs preferentially elute out using a 1.5 wt% SDS solution. Semiconductor-type SWCNTs are subsequently recovered from the column using a 2 wt% Pluronic F77 surfactant solution eluent. The semiconductor-enriched fraction purity is in the 90-95% range, based on detailed UV-vis-NIR absorption and resonant Raman spectroscopy characterization of the particulate suspension. Semiconductor-type SWCNTs are recovered in solid form by evaporating the suspension fluid, and heating the dried sample in air to a temperature just above the Pluronic decomposition temperature. Using Pluronic and other nonionic-type surfactants can aid the scalability of the chromatographic production of semiconducting SWCNT samples.
关键词： Carbon Nanotube,SWCNT,Semiconductor,Separation,Affinity Chromatography
更新于2025-09-23 15:21:01
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Application of Atom Probe Tomography to Complex Microstructures of Laser Additively Manufactured Samples
摘要： Additive Manufacturing (AM) technologies have gained increasing interest across multiple industrial sectors ranging from biomedical to aerospace. AM is not only used for prototyping, but also for tooling as well as for final part production. The computer-controlled, layer-by-layer building up process allows for increased design freedom enabling to produce almost any shape. Additional benefits are potential resource efficiency, increased product customization and lightweight design. Two prominent metal-based laser AM (LAM) techniques are laser powder bed fusion (LPBF) and laser metal deposition (LMD). In LPBF, a focused laser beam is scanned over a bed filled with metal powder to locally melt and fuse the powder to produce fully dense metal parts. The next layer of powder is then distributed and the laser scans again. LMD is a nozzle-based AM process in which a focused laser beam creates a melt pool in the build’s surface. Metallic powder is then injected into the melt pool through a nozzle. The 3D part is built by moving the nozzle/laser assembly forward track by track and layer by layer. Material produced by LAM exhibits a unique thermal history: initially, the material is cooled rapidly from the liquid state in the meltpool. Subsequently, the material experiences a cyclic reheating, the so-called intrinsic heat treatment (IHT), as neighboring tracks and further layers are deposited during the LAM process. Consequences of this thermal history are very complex, sometimes hierarchical microstructures with inhomogeneities at scales ranging from nanometers up millimeters. Fully understanding and characterizing these microstructures is challenging and requires the combination of methods spanning a similar range: from light optical microscopy (LOM) to electron microscopy to atom probe tomography (APT). Here we present examples how APT can deliver valuable information on complex microstructures to better understand the IHT, rapid solidification as well as phase separation in different metallic alloys. Here I will discuss examples in steel, Al- and Ni-based superalloys, and high entropy alloys (HEA).
关键词： Laser Additive Manufacturing,Additive Manufacturing,Phase Separation,Microstructures,Atom Probe Tomography,Rapid Solidification,Intrinsic Heat Treatment
更新于2025-09-23 15:19:57
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Impact of electrona??phonon coupling on the quantum yield of photovoltaic devices
摘要： In describing the charge carriers’ separation mechanism in the organic solar cell, providing a method, which considers the impact of all parameters of interest on the same footing within an inexpensive numerical effort, could play an essential role. We use here a simple tight-binding model to describe the dissociation of the charge carriers and investigate their dependence on the physical parameters of the system. We demonstrate that the quantum yield of the cell is subtly controlled by the collective action of the Coulomb interaction of the electron–hole pair, electron–phonon coupling, and the geminate recombination of the charge carriers. This approach should help us understand the performance of organic solar cells and optimize their efficiency.
关键词： electron–phonon coupling,quantum yield,organic solar cells,charge separation,photovoltaic devices
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Wide-aperture deformable mirrors for wavefront distortions compensation in high-power laser complexes
摘要： This paper addresses the determined blind source separation problem and proposes a new effective method unifying independent vector analysis (IVA) and nonnegative matrix factorization (NMF). IVA is a state-of-the-art technique that utilizes the statistical independence between sources in a mixture signal, and an efficient optimization scheme has been proposed for IVA. However, since the source model in IVA is based on a spherical multivariate distribution, IVA cannot utilize specific spectral structures such as the harmonic structures of pitched instrumental sounds. To solve this problem, we introduce NMF decomposition as the source model in IVA to capture the spectral structures. The formulation of the proposed method is derived from conventional multichannel NMF (MNMF), which reveals the relationship between MNMF and IVA. The proposed method can be optimized by the update rules of IVA and single-channel NMF. Experimental results show the efficacy of the proposed method compared with IVA and MNMF in terms of separation accuracy and convergence speed.
关键词： determined,independent vector analysis,Blind source separation,nonnegative matrix factorization
更新于2025-09-23 15:19:57
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Dry Magnetic Separation on the Recovery of Metal Fragments from Kerf Slurry Waste Produced during the Manufacture of Photovoltaic Solar Cells
摘要： In the interest of reducing the cost of photovoltaic production while preserving the environment, a sawing rejection treatment was carried out by recovering the metals with an efficiency estimated to be 96%. To achieve this outcome, first, the sawing rejection was washed with acetone to dissolve the polyethylene glycol. It was then dried in an oven at 70 °C to obtain a slurry powder. This later, powder has undergone a dry magnetic separation under different electric current intensity to recover metals. The metal-containing phase has been characterized by the X-ray diffractometer and the scanning electron microscope. Finally, a simulation on the recovery of metal fragments in the slurry generated during the manufacture of photovoltaic briquettes.
关键词： Metals,Slurry,Dry magnetic separation,Photovoltaic cell,Polyethylene glycol (PEG),Scanning electron microscopy (SEM)
更新于2025-09-23 15:19:57
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Simultaneous Power Conversion Efficiency and Stability Enhancement of Cs <sub/>2</sub> AgBiBr <sub/>6</sub> Leada??Free Inorganic Perovskite Solar Cell through Adopting a Multifunctional Dye Interlayer
摘要： Perovskite solar cells (PSCs) are highly promising next-generation photovoltaic devices because of the cheap raw materials, ideal band gap of ≈1.5 eV, broad absorption range, and high absorption coefficient. Although lead-based inorganic-organic PSC has achieved the highest power conversion efficiency (PCE) of 25.2%, the toxic nature of lead and poor stability strongly limits the commercialization. Lead-free inorganic PSCs are potential alternatives to toxic and unstable organic-inorganic PSCs. Particularly, double-perovskite Cs2AgBiBr6-based PSC has received interests for its all inorganic and lead-free features. However, the PCE is limited by the inherent and extrinsic defects of Cs2AgBiBr6 films. Herein, an effective and facile strategy is reported for improving the PCE and stability by introducing an N719 dye interlayer, which plays multifunctional roles such as broadening the absorption spectrum, suppressing the charge carrier recombination, accelerating the hole extraction, and constructing an appropriate energy level alignment. Consequently, the optimizing cell delivers an outstanding PCE of 2.84%, much improved as compared with other Cs2AgBiBr6-based PSCs reported so far in the literature. Moreover, the N719 interlayer greatly enhances the stability of PSCs under ambient conditions. This work highlights a useful strategy to boost the PCE and stability of lead-free Cs2AgBiBr6-based PSCs simultaneously, accelerating the commercialization of PSC technology.
关键词： charge carrier separation,dye interlayer,Cs2AgBiBr6,energy level alignment,perovskite solar cell
更新于2025-09-23 15:19:57
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Effective Separation and Recovery of Valuable Components from CIGS Chamber Waste via Controlled Phase Transformation and Selective Leaching
摘要： Copper indium gallium diselenide (CIGS) chamber waste formed during CIGS solar-cell production was subjected to two-stage sulfation roasting for controlled phase transformation and selective leaching to separate valuable components. Selenium was initially separated in the first stage of sulfation roasting. Under the optimal conditions, 99.96% of selenium was volatilized into gas in the form of selenium dioxide, and the remaining components were converted to sulfates. The second stage of roasting followed by water leaching was investigated for the separation and recovery of the remaining components in slag. Controlled phase transformation of sulfates was completed in the second stage roasting. Indium and gallium sulfates are converted to oxides, whereas CuSO4 remained nearly unchanged. Afterward, 95.90% of copper was selectively leached into liquor, and the leaching rates of indium and gallium were only 5.67% and 2.89%, respectively. Consequently, the content of mixed indium and gallium oxides in the leach residue was 91.09%. Exploratory experiments show that indium and gallium can be effectively separated via alkali leaching and precipitation. Therefore, effective separation of valuable metals from CIGS chamber waste was achieved based on the different physical and chemical properties of the components.
关键词： Phase transformation,Valuable components,Separation,Leaching,CIGS chamber waste
更新于2025-09-23 15:19:57