Combined Magnetic Imaging and Anisotropic Magnetoresistance Detection of Dipolar Skyrmions

Magnetic skyrmions are localized particle-like nontrivial swirls that are promising in building high-performance topological spintronic devices. The read-out functions in skyrmionic devices require the translation of magnetic skyrmions to electrical signals. Here, combined real-space magnetic imaging and anisotropic magnetoresistance studies on dipolar skyrmions are reported. A single skyrmion chain and single skyrmion are observed using Lorentz transmission electron microscopy imaging. Meanwhile, the field, helicity, and skyrmion count dependence of anisotropic magnetoresistance of the Fe₃Sn₂ nanostructures are obtained simultaneously. These results demonstrate that the anisotropic magnetoresistance of skyrmions is independent of the helicity and proportional to the skyrmion count. This study promotes read-out operations in skyrmion-based spintronic devices.     

Reduced Graphene Oxides Modified Bi2Te3 Nanosheets for Rapid Photo-Thermoelectric Catalytic Therapy of Bacteria-Infected Wounds

Temperature variation-induced thermoelectric catalytic efficiency of thermoelectric material is simultaneously restricted by its electrical conductivity, Seebeck coefficient, and thermal conductivity. Herein, Bi₂Te₃ nanosheets are in situ grown on reduced graphene oxides (rGO) to generate an efficient photo-thermoelectric catalyst (rGO-Bi₂Te₃). This system exhibits phonon scattering effect and extra carrier transport channels induced by the formed heterointerface between rGO and Bi₂Te₃, which improves the power factor value and reduces thermal conductivity, thus enhancing the thermoelectric performance of 2.13 times than single Bi₂Te₃. The photo-thermoelectric catalysis of rGO-Bi₂Te₃ significantly improves the reactive oxygen species yields, resulting from the effective electron–hole separation caused by the unique thermoelectric field and heterointerfaces of rGO-Bi₂Te₃. Correspondingly, the electrospinning membranes containing rGO-Bi₂Te₃ nanosheets exhibit high antibacterial efficiency in vivo (99.35 ± 0.29%), accelerated tissue repair ability, and excellent biosafety. This study provides an insight into heterointerface design in photo-thermoelectric catalysis.     

Exploring a Stable and Dense 3D Lead Chloride Hybrid with Emission of Self-Trapped Excitons toward X-Ray Scintillation

The exceptional photophysical properties of 3D organic–inorganic lead halide hybrids (OILHs) endow their significant potential for usage in optoelectronics, which has sparked intense research on novel 3D OILHs and associated applications. However, constructing new 3D OILHs based on large organic cations suffers from tough challenges due to the limitation of the Goldschmidt tolerance factor rule, let alone further explorations of their practical applications. Herein, a brand-new 3D lead chloride hybrid, (1MPZ)Pb₄Cl₁₀·H₂O ( 1 , 1MPZ = 1-methylpiperazine) is reported, featuring a dense 3D lead chloride framework made of the corner-, edge-, and face-shared lead chloride polyhedra. 1 presents a broadband white light emission with a large Stokes shift and a nanosecond photoluminescence lifetime, which originates from radiative recombination of self-trapped excitons (STEs) induced by the highly distorted structure. Such a reabsorption-free and fast-decayed STEs emission coupling with the dense 3D architecture further enables 1 with effective X-ray scintillation with good sensitivity. Impressively, 1 also shows superior environmental and radiation stability. This study provides a new 3D OILH with appealing luminescence, not only expanding the 3D OILH family but also inspiring the exploitation of their optoelectronic applications.     

19.28% Efficiency and Stable Polymer Solar Cells Enabled by Introducing an NIR-Absorbing Guest Acceptor

Here, a near-infrared (NIR)-absorbing small-molecule acceptor (SMA) Y-SeNF with strong intermolecular interaction and crystallinity is developed by combining selenophene-fused core with naphthalene-containing end-group, and then as a custom-tailor guest acceptor is incorporated into the binary PM6:L8-BO host system. Y-SeNF shows a 65 nm red-shifted absorption compared to L8-BO. Thanks to the strong crystallinity and intermolecular interaction of Y-SeNF, the morphology of PM6:L8-BO:Y-SeNF can be precisely regulated by introducing Y-SeNF, achieving improved charge-transporting and suppressed non-radiative energy loss. Consequently, ternary polymer solar cells (PSCs) offer an impressive device efficiency of 19.28% with both high photovoltage (0.873 V) and photocurrent (27.88 mA cm⁻²), which is one of the highest efficiencies in reported single-junction PSCs. Notably, ternary PSC has excellent stability under maximum-power-point tracking for even over 200 h, which is better than its parental binary devices. The study provides a novel strategy to construct NIR-absorbing SMA for efficient and stable PSCs toward practical applications.     

Identifying and Exploring Synthetic Antiferromagnetic Skyrmions

Synthetic antiferromagnetic (SAF) skyrmions are emerging as novel information carriers due to their high mobility and lack of a skyrmion Hall effect. However, distinguishing SAF skyrmions from their ferromagnetic counterparts using imaging techniques like magneto-optical microscopy remains challenging. While the suppressed intrinsic skyrmion Hall effect (SkHE) has been commonly used to identify SAF skyrmions, it is important to note that other factors such as defect pinning and dipolar interaction can also lead to a suppressed SkHE. Therefore, there is an urgent need for a universal identification method that can reliably differentiate SAF skyrmions from ferromagnetic ones. In this study, the generation of a SAF skyrmion within a standard SAF stack is demonstrated and its motion with almost no SkHE is investigated. Furthermore, a universal identification method is proposed wherein the application of an out-of-plane field allows the SAF skyrmion to be decoupled into two domains, which can either expand or contract with the application of an electric current. By expediting the development of a reliable means of identifying SAF skyrmions, these findings will accelerate the realization of practical applications based on these unique information carriers.     

In Situ Topochemical Transformation of ZnIn2S4 for Efficient Photocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Diformylfuran

Photocatalytic selective oxidation of 5-hydroxymethylfurfural (HMF) coupled H₂ production offers a promising approach to producing valuable chemicals. Herein, an efficient in situ topological transformation tactic is developed for producing porous O-doped ZnIn₂S₄ nanosheets for HMF oxidation cooperative with H₂ evolution. Aberration-corrected high-angle annular dark-field scanning TEM images show that the hierarchical porous O-ZIS-120 possesses abundant atomic scale edge steps and lattice defects, which is beneficial for electron accumulation and molecule adsorption. The optimal catalyst (O-ZIS-120) exhibits remarkable performance with 2,5-diformylfuran (DFF) yields of 1624 µmol h⁻¹ g⁻¹ and the selectivity of >97%, simultaneously with the H₂ evolution rate of 1522 µmol h⁻¹ g⁻¹. Mechanistic investigations through theoretical calculations show that O in the O-ZIS-120 lattice can reduce the oxidation energy barrier of hydroxyl groups of HMF. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) results reveal that DFF^* (C₄H₂(CHO)₂O^*) intermediate has a weak interaction with O-ZIS-120 and desorb as the final product. This study elucidates the topotactic structural transitions of 2D materials simultaneously with electronic structure modulation for efficient photocatalytic DFF production.     

Finite-Sized Atom Reconstruction Enhanced High-Frequency Multi-Domain Magnetic Response

The technological advances in wearable electronics and military stealth have spawned extensive research into electromagnetic wave absorbents. Despite the rapid progress in the geometrical modulation of magnetic absorbents, the engineering strategy of microwave-responsive magnetic domains is underdeveloped and the response dynamics remain unclear. Herein, a surface finite-sized atom reconstruction procedure is proposed to accurately modulate the local magnetic topological domains, dramatically enhancing the magnetic loss capacity. Due to the selectivity of atom reconstruction, vortex and stripe domains are controllably hybridized around the porous surface to broaden the interactive domain region, significantly intensifying energy absorption of the microwave field. Meanwhile, the amorphous/crystalline interfaces around atom reconstruction regions can induce interfacial polarization, enabling the optimization of dielectric loss capacity. Therefore, a satisfactory magnetic–dielectric synergy is realized to demonstrate the strong absorption intensity of −31.2 dB and the broad absorption bandwidth of 5.9 GHz. Furthermore, the surface-based magnetic domain transformation and microwave energy attenuation mechanisms are thoroughly revealed to break the black box of structure–function through electron holography and micromagnetic simulation. These achievements demonstrate a promising solution to improve high-frequency magnetic properties and provide a feasible route to interpret the structure-relevant magnetic loss capacity.     

无线通信信道技术的研究

无线信道中最为复杂的是电波的传播特性,这些传播特性主要有中波、长波地表面波传播、电离层反射传播、还有各种散射波的传播等等。无线信道的干扰形式颇为繁多、它的特征十分复杂,本文主要针对无线通信信道技术的特点、分类、基本特征和发展现状,做出相应的研究。     

Implementation of a High Throughput 3GPP Turbo Decoder on GPU

Turbo code is a computationally intensive channel code that is widely used in current and upcoming wireless standards. General-purpose graphics processor unit (GPGPU) is a programmable commodity processor that achieves high performance computation power by using many simple cores. In this paper, we present a 3GPP LTE compliant Turbo decoder accelerator that takes advantage of the processing power of GPU to offer fast Turbo decoding throughput. Several techniques are used to improve the performance of the decoder. To fully utilize the computational resources on GPU, our decoder can decode multiple codewords simultaneously, divide the workload for a single codeword across multiple cores, and pack multiple codewords to fit the single instruction multiple data (SIMD) instruction width. In addition, we use shared memory judiciously to enable hundreds of concurrent multiple threads while keeping frequently used data local to keep memory access fast. To improve efficiency of the decoder in the high SNR regime, we also present a low complexity early termination scheme based on average extrinsic LLR statistics. Finally, we examine how different workload partitioning choices affect the error correction performance and the decoder throughput.