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In Situ Epitaxy of Pure Phase Ultra-Thin InAs-Al Nanowires for Quantum Devices
Dong Pan, Huading Song, Shan Zhang, Lei Liu, Lianjun Wen, Dunyuan Liao, Ran Zhuo, Zhichuan Wang, Zitong Zhang, Shuai Yang, Jianghua Ying, Wentao Miao, Runan Shang, Hao Zhang, and Jianhua Zhao
Chin. Phys. Lett.    2022, 39 (5): 058101 .   DOI: 10.1088/0256-307X/39/5/058101
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We demonstrate the in situ growth of ultra-thin InAs nanowires with an epitaxial Al film by molecular-beam epitaxy. Our InAs nanowire diameter ($\sim $30 nm) is much thinner than before ($\sim $100 nm). The ultra-thin InAs nanowires are pure phase crystals for various different growth directions. Transmission electron microscopy confirms an atomically abrupt and uniform interface between the Al shell and the InAs wire. Quantum transport study on these devices resolves a hard induced superconducting gap and 2$e$-periodic Coulomb blockade at zero magnetic field, a necessary step for future Majorana experiments. By reducing wire diameter, our work presents a promising route for reaching fewer sub-band regime in Majorana nanowire devices.
Large Room-Temperature Magnetoresistance in van der Waals Ferromagnet/Semiconductor Junctions
Wenkai Zhu, Shihong Xie, Hailong Lin, Gaojie Zhang, Hao Wu, Tiangui Hu, Ziao Wang, Xiaomin Zhang, Jiahan Xu, Yujing Wang, Yuanhui Zheng, Faguang Yan, Jing Zhang, Lixia Zhao, Amalia Patanè, Jia Zhang, Haixin Chang, and Kaiyou Wang
Chin. Phys. Lett.    2022, 39 (12): 128501 .   DOI: 10.1088/0256-307X/39/12/128501
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A magnetic tunnel junction (MTJ) is the core component in memory technologies, such as the magnetic random-access memory, magnetic sensors and programmable logic devices. In particular, MTJs based on two-dimensional van der Waals (vdW) heterostructures offer unprecedented opportunities for low power consumption and miniaturization of spintronic devices. However, their operation at room temperature remains a challenge. Here, we report a large tunnel magnetoresistance (TMR) of up to 85% at room temperature ($T = 300$ K) in vdW MTJs based on a thin ($ < 10$ nm) semiconductor spacer WSe$_{2}$ layer embedded between two Fe$_{3}$GaTe$_{2}$ electrodes with intrinsic above-room-temperature ferromagnetism. The TMR in the MTJ increases with decreasing temperature up to 164% at $T = 10$ K. The demonstration of TMR in ultra-thin MTJs at room temperature opens a realistic and promising route for next-generation spintronic applications beyond the current state of the art.
A 700 W$\cdot$h$\cdot$kg$^{-1}$ Rechargeable Pouch Type Lithium Battery
Quan Li, Yang Yang, Xiqian Yu, and Hong Li
Chin. Phys. Lett.    2023, 40 (4): 048201 .   DOI: 10.1088/0256-307X/40/4/048201
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High-energy-density rechargeable lithium batteries are being pursued by researchers because of their revolutionary potential nature. Current advanced practical lithium-ion batteries have an energy density of around 300 W$\cdot$h$\cdot$kg$^{-1}$. Continuing to increase the energy density of batteries to a higher level could lead to a major explosion development in some fields, such as electric aviation. Here, we have manufactured practical pouch-type rechargeable lithium batteries with both a gravimetric energy density of 711.3 W$\cdot$h$\cdot$kg$^{-1}$ and a volumetric energy density of 1653.65 W$\cdot$h$\cdot$L$^{-1}$. This is achieved through the use of high-performance battery materials including high-capacity lithium-rich manganese-based cathode and thin lithium metal anode with high specific energy, combined with extremely advanced process technologies such as high-loading electrode preparation and lean electrolyte injection. In this battery material system, the structural stability of cathode material in a widened charge/discharge voltage range and the deposition/dissolution behavior of interfacial modified thin lithium electrode are studied.
Recent Progress in Presodiation Technique for High-Performance Na-Ion Batteries
Fei Xie , Yaxiang Lu, Liquan Chen , and Yong-Sheng Hu
Chin. Phys. Lett.    2021, 38 (11): 118401 .   DOI: 10.1088/0256-307X/38/11/118401
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Na-ion batteries (NIBs) have been attracting growing interests in recent years with the increasing demand of energy storage owing to their dependence on more abundant Na than Li. The exploration of the industrialization of NIBs is also on the march, where some challenges are still limiting its step. For instance, the relatively low initial Coulombic efficiency (ICE) of anode can cause undesired energy density loss in the full cell. In addition to the strategies from the sight of materials design that to improve the capacity and ICE of electrodes, presodiation technique is another important method to efficiently offset the irreversible capacity and enhance the energy density. Meanwhile, the slow release of the extra Na during the cycling is able to improve the cycling stability. In this review, we would like to provide a general insight of presodiation technique for high-performance NIBs. The recent research progress including the principles and strategies of presodiation will be introduced, and some remaining challenges as well as our perspectives will be discussed. This review aims to exhibit the basic knowledge of presodiation to inspire the researchers for future studies.
Giant Tunneling Magnetoresistance in Spin-Filter Magnetic Tunnel Junctions Based on van der Waals A-Type Antiferromagnet CrSBr
Guibin Lan, Hongjun Xu, Yu Zhang, Chen Cheng, Bin He, Jiahui Li, Congli He, Caihua Wan, Jiafeng Feng, Hongxiang Wei, Jia Zhang, Xiufeng Han, and Guoqiang Yu
Chin. Phys. Lett.    2023, 40 (5): 058501 .   DOI: 10.1088/0256-307X/40/5/058501
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Two-dimensional van der Waals magnetic materials have demonstrated great potential for new-generation high-performance and versatile spintronic devices. Among them, magnetic tunnel junctions (MTJs) based on A-type antiferromagnets, such as CrI$_{3}$, possess record-high tunneling magnetoresistance (TMR) because of the spin filter effect of each insulating unit ferromagnetic layer. However, the relatively low working temperature and the instability of the chromium halides hinder applications of this system. Using a different technical scheme, we fabricated the MTJs based on an air-stable A-type antiferromagnet, CrSBr, and observed a giant TMR of up to 47000% at 5 K. Meanwhile, because of a relatively high Néel temperature of CrSBr, a sizable TMR of about 50% was observed at 130 K, which makes a big step towards spintronic devices at room temperature. Our results reveal the potential of realizing magnetic information storage in CrSBr-based spin-filter MTJs.
Fluorination Increases Hydrophobicity at the Macroscopic Level but not at the Microscopic Level
Weishuai Di, Xin Wang, Yanyan Zhou, Yuehai Mei, Wei Wang, and Yi Cao
Chin. Phys. Lett.    2022, 39 (3): 038701 .   DOI: 10.1088/0256-307X/39/3/038701
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Hydrophobic interactions have been studied before in detail based on hydrophobic polymers, such as polystyrene (PS). Because fluorinated materials have relatively low surface energy, they often show both oleophobicity and hydrophobicity at the macroscopic level. However, it remains unknown how fluorination of hydrophobic polymer influences hydrophobicity at the microscopic level. We synthesized PS and fluorine-substituted PS (FPS) by employing the reversible addition-fragmentation chain transfer polymerization method. Contact angle measurements confirmed that FPS is more hydrophobic than PS at the macroscopic level due to the introduction of fluorine. However, single molecule force spectroscopy experiments showed that the forces required to unfold the PS and FPS nanoparticles in water are indistinguishable, indicating that the strength of the hydrophobic effect that drives the self-assembly of PS and FPS nanoparticles is the same at the microscopic level. The divergence of hydrophobic effect at the macroscopic and microscopic level may hint different underlying mechanisms: the hydrophobicity is dominated by the solvent hydration at the microscopic level and the surface-associated interaction at the macroscopic level.
Thermal Management of Air-Cooling Lithium-Ion Battery Pack
Jianglong Du, Haolan Tao, Yuxin Chen, Xiaodong Yuan, Cheng Lian, and Honglai Liu
Chin. Phys. Lett.    2021, 38 (11): 118201 .   DOI: 10.1088/0256-307X/38/11/118201
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Lithium-ion battery packs are made by many batteries, and the difficulty in heat transfer can cause many safety issues. It is important to evaluate thermal performance of a battery pack in designing process. Here, a multiscale method combining a pseudo-two-dimensional model of individual battery and three-dimensional computational fluid dynamics is employed to describe heat generation and transfer in a battery pack. The effect of battery arrangement on the thermal performance of battery packs is investigated. We discuss the air-cooling effect of the pack with four battery arrangements which include one square arrangement, one stagger arrangement and two trapezoid arrangements. In addition, the air-cooling strategy is studied by observing temperature distribution of the battery pack. It is found that the square arrangement is the structure with the best air-cooling effect, and the cooling effect is best when the cold air inlet is at the top of the battery pack. We hope that this work can provide theoretical guidance for thermal management of lithium-ion battery packs.
High-Sensitivity Tunnel Magnetoresistance Sensors Based on Double Indirect and Direct Exchange Coupling Effect
Xiufeng Han, Yu Zhang, Yizhan Wang, Li Huang, Qinli Ma, Houfang Liu, Caihua Wan, Jiafeng Feng, Lin Yin, Guoqiang Yu, Tian Yu, and Yu Yan
Chin. Phys. Lett.    2021, 38 (12): 128501 .   DOI: 10.1088/0256-307X/38/12/128501
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Detection of ultralow magnetic field requires magnetic sensors with high sensitivity and low noise level, especially for low operating frequency applications. We investigated the transport properties of tunnel magnetoresistance (TMR) sensors based on the double indirect exchange coupling effect. The TMR ratio of about 150% was obtained in the magnetic tunnel junctions and linear response to an in-plane magnetic field was successfully achieved. A high sensitivity of 1.85%/Oe was achieved due to a designed soft pinned sensing layer of CoFeB/NiFe/Ru/IrMn. Furthermore, the voltage output sensitivity and the noise level of 10.7 mV/V/Oe, 10 nT/Hz$^{1/2}$ at 1 Hz and 3.3 nT/Hz$^{1/2}$ at 10 Hz were achieved in Full Wheatstone Bridge configuration. This kind of magnetic sensors can be used in the field of smart grid for current detection and sensing.
Coulomb Thermoelectric Drag in Four-Terminal Mesoscopic Quantum Transport
Mengmeng Xi, Rongqian Wang, Jincheng Lu, and Jian-Hua Jiang
Chin. Phys. Lett.    2021, 38 (8): 088801 .   DOI: 10.1088/0256-307X/38/8/088801
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We show that the Coulomb interaction between two circuits separated by an insulating layer leads to unconventional thermoelectric effects, such as the cooling by thermal current effect, the transverse thermoelectric effect and Maxwell's demon effect. The first refers to cooling in one circuit induced by the thermal current in the other circuit. The middle represents electric power generation in one circuit by the temperature gradient in the other circuit. The physical picture of Coulomb drag between the two circuits is first demonstrated for the case with one quantum dot in each circuit and it is then elaborated for the case with two quantum dots in each circuit. In the latter case, the heat exchange between the two circuits can vanish. Finally, we also show that the Maxwell's demon effect can be realized in the four-terminal quantum dot thermoelectric system, in which the quantum system absorbs the heat from the high-temperature heat bath and releases the same heat to the low-temperature heat bath without any energy exchange with the two heat baths. Our study reveals the role of Coulomb interaction in non-local four-terminal thermoelectric transport.
Highly Sensitive Mid-Infrared Photodetector Enabled by Plasmonic Hot Carriers in the First Atmospheric Window
Yuan-Fang Yu, Ye Zhang, Fan Zhong, Lin Bai, Hui Liu, Jun-Peng Lu, and Zhen-Hua Ni
Chin. Phys. Lett.    2022, 39 (5): 058501 .   DOI: 10.1088/0256-307X/39/5/058501
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The first atmospheric window of 3–5 µm in the mid-infrared (MIR) spectral range pertains to crucial application fields, with particular scientific and technological importance. However, conventional narrow-bandgap semiconductors operating at this band, represented by mercury cadmium telluride and indium antimonide, suffer from limited specific detectivity at room temperature and hindered optoelectronic integration. In this study, a plasmonic hot electron-empowered MIR photodetector based on Al-doped ZnO (AZO)/bi-layer graphene heterostructure is demonstrated. Free electrons oscillate coherently in AZO disk arrays, resulting in strong localized surface plasmon resonance (LSPR) in the MIR region. The photoelectric conversion efficiency at 3–5 µm is significantly improved due to plasmon-induced hot-electron extraction and LSPR-enhanced light absorption. The specific detectivity reaches about $1.4 \times 10^{11}$ Jones and responsivity is up to 4712.3 A/W at wavelength of 3 µm at room temperature. The device's specific detectivity is among the highest performance of commercial state-of-the-art photodetectors and superior to most of the other 2D materials based photodetectors in the MIR region. These results demonstrate that a plasmonic heavily doped metal oxides/2D material heterostructure is a suitable architecture for constructing highly sensitive room-temperature MIR photodetectors.
New Insight of Fe Valence State Change Using Leaves: A Combined Experimental and Theoretical Study
Zejun Zhang, Yizhou Yang, Jie Jiang, Liang Chen, Shanshan Liang, and Haiping Fang
Chin. Phys. Lett.    2022, 39 (10): 108201 .   DOI: 10.1088/0256-307X/39/10/108201
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Fe$^{2+}$ is of considerable importance in plant growth and crop production. However, most Fe elements in nature favor existing in the trivalent state, which often causes the deficiency of Fe$^{2+}$ in plants. Here, we report the Fe valence state change from Fe$^{3+}$ to Fe$^{2+}$ by using leaves. This valence state change was confirmed by x-ray photoelectron spectroscopy in Fe-Cl@leaves. Fourier transform infrared and ultraviolet-visible spectroscopy demonstrated that aromatic ring groups were included in leaves, and cation-$\pi$ interactions between Fe cations and the components containing aromatic rings in leaves were measured. Further, density functional theory calculations revealed that the most stable adsorption site for hydrated Fe$^{3+}$ cation was the region where hydroxyl groups and aromatic rings coexist. Moreover, molecular orbital and charge decomposition analysis revealed that the aromatic rings took the major part (59%) of the whole net charge transfer between leaves and Fe cations. This work provides a high-efficiency and eco-friendly way to transform the Fe valence state from Fe$^{3+}$ to Fe$^{2+}$, and affords a new insight into the valance change between plant organisms with cations.
Effect of Fluorine Substitution on the Electrochemical Property and Structural Stability of a Lithium-Excess Cation Disordered Rock-Salt Cathode
Panpan Li , Zhijie Feng , Tao Cheng , Yingchun Lyu, and Bingkun Guo
Chin. Phys. Lett.    2021, 38 (8): 088201 .   DOI: 10.1088/0256-307X/38/8/088201
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Lithium-excess cation disordered rock-salt materials have received much attention because of their high-capacity as a candidate for cathodes for lithium-ion batteries. The ultra-high specific capacity comes from the coordinated charge compensation of both transition metal and lattice oxygen. However, the oxygen redox at high voltage usually leads to irreversible oxygen release, thereby degrading the structure stability and electrochemical performance. Lithium-excess Li$_{1.14}$Ni$_{0.57+0.5 x}$Ti$_{0.19-0.5 x}$Mo$_{0.10}$O$_{2-x}$F$_{x}$ ($x=0$, 0.05, 0.10, 0.15, and 0.20) with different amounts of fluorine substitution were synthesized. Among them, Li$_{1.14}$Ni$_{0.620}$Ti$_{0.140}$Mo$_{0.10}$O$_{1.85}$F$_{0.15}$ exhibits a lower capacity decline, better rate performance, and lower structure damage. The effects of fluorine substitution on the electrochemical property and structural stability were systematic studied by x-ray photoelectron spectroscopy and in situ XRD etc. Results show that fluorine substitution reduces the average valence of the anion, allowing a larger proportion of low-valent redox active transition metals, increasing the transition metal redox capacity, inhibiting irreversible oxygen release and side reaction. Fluorine substitution further improves the structural stability and suppresses lattice deformation of the material.
Low-Temperature Aqueous Na-Ion Batteries: Strategies and Challenges of Electrolyte Design
Qiubo Guo, Shuai Han, Yaxiang Lu, Liquan Chen, and Yong-Sheng Hu
Chin. Phys. Lett.    2023, 40 (2): 028801 .   DOI: 10.1088/0256-307X/40/2/028801
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Aqueous Na-ion batteries (ANIBs) are considered to be promising secondary battery systems for grid-scale energy storage applications and have attracted widespread attention due to their unique merits of rich resources of Na, as well as the inherent safety and low cost of aqueous electrolytes. However, the narrow electrochemical stability widow and high freezing point of traditional dilute aqueous electrolytes restrict their multi-scenario applications. Considering the charge-storage mechanism of ANIBs, the optimization and design of aqueous Na-based electrolytes dominate their low-temperature performance, which is also hot off the press in this field. In this review, we first systematically comb the research progress of the novel electrolytes and point out their remaining challenges in ANIBs. Then our perspectives on how to further improve the low-temperature performance of ANIBs will also be discussed. Finally, this review briefly sheds light on the potential direction of low-temperature ANIBs, which would guide the future design of high-performance aqueous rechargeable batteries.
Achieving 1.2 fm/Hz$^{1/2}$ Displacement Sensitivity with Laser Interferometry in Two-Dimensional Nanomechanical Resonators: Pathways towards Quantum-Noise-Limited Measurement at Room Temperature
Jiankai Zhu, Luming Wang, Jiaqi Wu, Yachun Liang, Fei Xiao, Bo Xu, Zejuan Zhang, Xiulian Fan, Yu Zhou, Juan Xia, and Zenghui Wang
Chin. Phys. Lett.    2023, 40 (3): 038102 .   DOI: 10.1088/0256-307X/40/3/038102
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Laser interferometry is an important technique for ultrasensitive detection of motion and displacement. We push the limit of laser interferometry through noise optimization and device engineering. The contribution of noises other than shot noise is reduced from 92.6% to 62.4%, demonstrating the possibility towards shot-noise-limited measurement. Using noise thermometry, we quantify the laser heating effect and determine the range of laser power values for room-temperature measurements. With detailed analysis and optimization of signal transduction, we achieve 1.2 fm/Hz$^{1/2}$ displacement measurement sensitivity at room temperature in two-dimensional (2D) CaNb$_{2}$O$_{6}$ nanomechanical resonators, the best value reported to date among all resonators based on 2D materials. Our work demonstrates a possible pathway towards quantum-noise-limited measurement at room temperature.
Epitaxial Growth and Characteristics of Nonpolar $a$-Plane InGaN Films with Blue-Green-Red Emission and Entire In Content Range
Jianguo Zhao, Kai Chen, Maogao Gong, Wenxiao Hu, Bin Liu, Tao Tao, Yu Yan, Zili Xie, Yuanyuan Li, Jianhua Chang, Xiaoxuan Wang, Qiannan Cui, Chunxiang Xu, Rong Zhang, and Youdou Zheng
Chin. Phys. Lett.    2022, 39 (4): 048101 .   DOI: 10.1088/0256-307X/39/4/048101
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Nonpolar (11$\bar{2}$0) plane In$_{x}$Ga$_{1- x}$N epilayers comprising the entire In content ($x$) range were successfully grown on nanoscale GaN islands by metal-organic chemical vapor deposition. The structural and optical properties were studied intensively. It was found that the surface morphology was gradually smoothed when $x$ increased from 0.06 to 0.33, even though the crystalline quality was gradually declined, which was accompanied by the appearance of phase separation in the In$_{x}$Ga$_{1- x}$N layer. Photoluminescence wavelengths of 478 and 674 nm for blue and red light were achieved for $x$ varied from 0.06 to 0.33. Furthermore, the corresponding average lifetime ($\tau_{1/e}$) of carriers for the nonpolar InGaN film was decreased from 406 ps to 267 ps, indicating that a high-speed modulation bandwidth can be expected for nonpolar InGaN-based light-emitting diodes. Moreover, the bowing coefficient ($b$) of the (11$\bar{2}$0) plane InGaN was determined to be 1.91 eV for the bandgap energy as a function of $x$.
Enhanced Anomalous Hall Effect of Pt on an Antiferromagnetic Insulator with Fully Compensated Surface
Yu Bai, Zhe Wang, Na Lei, Wisal Muhammad, Lifeng Xiang, Qiang Li, Huilin Lai, Yinyan Zhu, Wenbing Wang, Hangwen Guo, Lifeng Yin, Ruqian Wu, and Jian Shen
Chin. Phys. Lett.    2022, 39 (10): 108501 .   DOI: 10.1088/0256-307X/39/10/108501
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We report a significantly enhanced anomalous Hall effect (AHE) of Pt on antiferromagnetic insulator thin film (3-unit-cell La$_{0.7}$Sr$_{0.3}$MnO$_{3}$, abbreviated as LSMO), which is one order of magnitude larger than that of Pt on other ferromagnetic (e.g. Y$_{3}$Fe$_{5}$O$_{12}$) and antiferromagnetic (e.g. Cr$_{2}$O$_{3}$) insulator thin films. Our experiments demonstrate that the antiferromagnetic La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ with fully compensated surface suppresses the positive anomalous Hall resistivity induced by the magnetic proximity effect and facilitates the negative anomalous Hall resistivity induced by the spin Hall effect. By changing the substrate's temperature during Pt deposition, we observed that the diffusion of Mn atoms into Pt layer can further enhance the AHE. The anomalous Hall resistivity increases with increasing temperature and persists even well above the Neel temperature ($T_{\rm N}$) of LSMO. The Monte Carlo simulations manifest that the unusual rise of anomalous Hall resistivity above $T_{\rm N}$ originates from the thermal induced magnetization in the antiferromagnetic insulator.
Edge Transport and Self-Assembly of Passive Objects in a Chiral Active Fluid
Qing Yang, Huan Liang, Rui Liu, Ke Chen, Fangfu Ye, and Mingcheng Yang
Chin. Phys. Lett.    2021, 38 (12): 128701 .   DOI: 10.1088/0256-307X/38/12/128701
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Topological edge flow and dissipationless odd viscosity are two remarkable features of chiral active fluids composed of active spinners. These features can significantly influence the dynamics of suspended passive particles and the interactions between the particles. By computer simulations, we investigate the transport phenomenon of anisotropic passive objects and the self-assembly behavior of passive spherical particles in the active spinner fluid. It is found that in confined systems, nonspherical passive objects can stably cling to boundary walls and are unidirectionally and robustly transported by edge flow of spinners. Furthermore, in an unconfined system, passive spherical particles are able to form stable clusters that spontaneously and unidirectionally rotate as a whole. In these phenomena, strong particle-wall and interparticle effective attractions play a vital role, which originate from spinner-mediated depletion-like interactions and can be largely enhanced by odd viscosity of spinner fluids. Our results thus provide new insight into the robust transport of cargoes and the nonequilibrium self-assembly of passive intruders.
Elastic Modulus, Hardness, and Fracture Toughness of Li$_{6.4}$La$_{3}$Zr$_{1.4}$Ta$_{0.6}$O$_{12}$ Solid Electrolyte
Shan Hu, Pengyu Xu, Luize Scalco de Vasconcelos, Lia Stanciu, Hongwei Ni, and Kejie Zhao
Chin. Phys. Lett.    2021, 38 (9): 098401 .   DOI: 10.1088/0256-307X/38/9/098401
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Li$_{6.4}$La$_{3}$Zr$_{1.4}$Ta$_{0.6}$O$_{12}$ (LLZTO) is a promising inorganic solid electrolyte due to its high Li$^{+}$ conductivity and electrochemical stability for all-solid-state batteries. Mechanical characterization of LLZTO is limited by the synthesis of the condensed phase. Here we systematically measure the elastic modules, hardness, and fracture toughness of LLZTO polycrystalline pellets of different densities using the customized environmental nanoindentation. The LLZTO samples are sintered using the hot-pressing method with different amounts of Li$_{2}$CO$_{3}$ additives, resulting in the relative density of the pellets varying from 83% to 98% and the largest grain size of $13.21 \pm 5.22$ µm. The mechanical properties show a monotonic increase as the sintered sample densifies, elastic modulus and hardness reach $158.47 \pm 10.10$ GPa and $11.27 \pm 1.38$ GPa, respectively, for LLZTO of 98% density. Similarly, fracture toughness increases from 0.44 to 1.51 MPa$\cdot$m$^{1/2}$, showing a transition from the intergranular to transgranular fracture behavior as the pellet density increases. The ionic conductivity reaches $4.54 \times 10^{-4}$ S/cm in the condensed LLZTO which enables a stable Li plating/stripping in a symmetric solid-state cell for over 100 cycles. This study puts forward a quantitative study of the mechanical behavior of LLZTO of different microstructures that is relevant to the mechanical stability and electrochemical performance of all-solid-state batteries.
A Ferroelectric Domain-Wall Transistor
Yang-Jun Ou, Jie Sun, Yi-Ming Li, and An-Quan Jiang
Chin. Phys. Lett.    2023, 40 (3): 038501 .   DOI: 10.1088/0256-307X/40/3/038501
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On the basis of novel properties of ferroelectric conducting domain walls, the domain wall nanoelectronics emerges and provides a brand-new dimension for the development of high-density, high-speed and energy-efficient nanodevices. For in-memory computing, three-terminal devices with both logic and memory functions such as transistors purely based on ferroelectric domain walls are urgently required. Here, a prototype ferroelectric domain-wall transistor with a well-designed coplanar electrode geometry is demonstrated on epitaxial BiFeO$_{3}$ thin films. For the logic function, the current switching between on/off states of the transistor depends on the creation or elimination of conducting domain walls between drain and source electrodes. For the data storage, the transistor can maintain nonvolatile on/off states after the write/erase operations, providing an innovative approach for the development of the domain wall nanoelectronics.
Acceleration of DNA Replication of Klenow Fragment by Small Resisting Force
Yu-Ru Liu, Peng-Ye Wang, Wei Li, and Ping Xie
Chin. Phys. Lett.    2021, 38 (11): 118701 .   DOI: 10.1088/0256-307X/38/11/118701
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DNA polymerases are an essential class of enzymes or molecular motors that catalyze processive DNA syntheses during DNA replications. A critical issue for DNA polymerases is their molecular mechanism of processive DNA replication. We have proposed a model for chemomechanical coupling of DNA polymerases before, based on which the predicted results have been provided about the dependence of DNA replication velocity upon the external force on Klenow fragment of DNA polymerase I. Here, we performed single molecule measurements of the replication velocity of Klenow fragment under the external force by using magnetic tweezers. The single molecule data verified quantitatively the previous theoretical predictions, which is critical to the chemomechanical coupling mechanism of DNA polymerases. A prominent characteristic for the Klenow fragment is that the replication velocity is independent of the assisting force whereas the velocity increases largely with the increase of the resisting force, attains the maximum velocity at about 3.8 pN and then decreases with the further increase of the resisting force.
Probing the Air Storage Failure Mechanism of Ni-Rich Layered Cathode Materials
Qingyu Dong, Ruowei Yi, Jizhen Qi, Yanbin Shen, and Liwei Chen
Chin. Phys. Lett.    2022, 39 (3): 038201 .   DOI: 10.1088/0256-307X/39/3/038201
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Ni-rich layered oxide cathode materials, such as LiNi$_{0.83}$Co$_{0.12}$Mn$_{0.05}$O$_{2}$ (NCM811), exhibit high specific capacity and low cost, and become cathode material preference of high-energy-density Li-ion batteries. However, these cathode materials are not stable and will form Li-poor reconstructed layers and alkaline compounds (Li$_{2}$CO$_{3}$, LiOH) on the surface during the storage and processing in humid air, resulting in serious deterioration of electrochemical properties. During the past two decades, the consensus on the surface instability mechanism during humid air storage has not been reached. The main controversy focuses on the unstable octahedron mechanism and the Li/H exchange mechanism. Herein, we investigate the instability mechanism in the humid air by conducting scanning electronic microscopy, scanning transmission electron microscopy, and x-ray photoelectron spectroscopy analysis on NCM811 samples stored in designed atmospheres, etc., and realize that the surface instability of the NCM811 during storage should be mainly originated from Li/H exchange when it contacts with moisture.
Large-Area Monolayer n-Type Molecular Semiconductors with Improved Thermal Stability and Charge Injection
Sai Jiang, Lichao Peng, Xiaosong Du, Qinyong Dai, Jianhang Guo, Jianhui Gu, Jian Su, Ding Gu, Qijing Wang, Huafei Guo, Jianhua Qiu, and Yun Li
Chin. Phys. Lett.    2023, 40 (3): 038101 .   DOI: 10.1088/0256-307X/40/3/038101
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We fabricated monolayer n-type two-dimensional crystalline semiconducting films with millimeter-sized areas and remarkable morphological uniformity using an antisolvent-confined spin-coating method. The antisolvent can cause a downstream Marangoni flow, which improves the film morphologies. The deposited crystalline monolayer films exhibit excellent thermal stabilities after annealing, which reveals the annealing-induced enhancement of crystallinity. The transistors based on the n-type monolayer crystalline films show linear output characteristics and superior electron mobilities. The improved charge injection between monolayer films and Au electrodes results from the energy level shift as the films decrease to the monolayer, which leads to a lower injection barrier. This work demonstrates a promising method for fabricating air-stable, low-cost, high-performance, and large-area organic electronics.
Modulated Collective Motions and Condensation of Bacteria
Mei-Mei Bao, Isaiah Eze Igwe, Kang Chen, and Tian-Hui Zhang
Chin. Phys. Lett.    2022, 39 (10): 108702 .   DOI: 10.1088/0256-307X/39/10/108702
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Bacteria can spontaneously develop collective motions by aligning their motions in dense systems. Here we show that bacteria can also respond collectively to an alternating electrical field and form dynamic clusters oscillating at the same frequency of the field. As the dynamic clusters go beyond a critical size, they split into smaller ones spontaneously. The critical size for splitting depends on the frequency of electric field and the concentration of bacteria. We show that, instead of their biological activity, the physical properties of bacteria as charged particles are responsible for the formation of dynamic clusters. Electroconvective flows across the system play the key role in stabilizing the clusters. However, to form clusters, collective hydrodynamic cooperation between bacteria is important such that no aggregation occurs in dilute suspensions. The findings in this study illustrate that bio-systems can respond collectively to an external field, promising an effective way to control and modulate the behavior of organisms. Moreover, the controlled aggregation and condensation of bacteria offer a robust approach to improve the local concentration of bacteria for early and rapid detection, which has wide applications in clinics.
Characteristics and Applications of Current-Driven Magnetic Skyrmion Strings
Zhaonian Jin, Minhang Song, Henan Fang, Lin Chen, Jiangwei Chen, and Zhikuo Tao
Chin. Phys. Lett.    2022, 39 (10): 108502 .   DOI: 10.1088/0256-307X/39/10/108502
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We investigate the current-driven characteristics and applications of magnetic skyrmion strings by micromagnetic simulations. Under the spin-polarized driving current, the skyrmion string presents different moving trajectories in different layers due to the skyrmion Hall effect. Moreover, a series of skyrmion bobbers can be generated with a notch defect placed in the surface and the skyrmion bobbers will follow the skyrmion string. By varying the current density, the bobbers' characteristics such as number and velocity can be manipulated, which inspires us to propose a skyrmion string-based diode. In addition, an AND logic gate and an OR logic gate in the identical scheme based on the skyrmion string are proposed. AND logic and OR logic behaviors can be realized by varying the driving current densities. Our findings will contribute to further research of magnetic skyrmion strings for data storage, processing, and energy-efficient computing.
Temperature-Dependent Far-Infrared Absorption in Cyclotrimethylene Trinitramine Single Crystals Using Broadband Time-Domain Terahertz Spectroscopy
Yupeng Liu, Jinchun Shi, and Chongyang Chen
Chin. Phys. Lett.    2022, 39 (1): 018701 .   DOI: 10.1088/0256-307X/39/1/018701
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We investigate the absorption properties of cyclotrimethylene trinitramine (RDX) single crystals from $\sim$15 to 150 cm$^{-1}$ using the terahertz time-domain spectroscopy. We observe that all the absorption modes exhibit strong anisotropic behavior in terms of the crystal orientations. We demonstrate that the anharmonic phonon model can well describe the temperature-dependent behaviors of these absorption modes. These results indicate that the intermolecular interaction plays a major role in the collective motion of large number of RDX molecules. Our findings provide important information for understanding and controlling the dynamic properties in the explosive materials.
Indium-Gallium-Zinc-Oxide-Based Photoelectric Neuromorphic Transistors for Spiking Morse Coding
Xinhuang Lin, Haotian Long, Shuo Ke, Yuyuan Wang, Ying Zhu, Chunsheng Chen, Changjin Wan, and Qing Wan
Chin. Phys. Lett.    2022, 39 (6): 068501 .   DOI: 10.1088/0256-307X/39/6/068501
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The human brain that relies on neural networks communicated by spikes is featured with ultralow energy consumption, which is more robust and adaptive than any digital system. Inspired by the spiking framework of the brain, spike-based neuromorphic systems have recently inspired intensive attention. Therefore, neuromorphic devices with spike-based synaptic functions are considered as the first step toward this aim. Photoelectric neuromorphic devices are promising candidates for spike-based synaptic devices with low latency, broad bandwidth, and superior parallelism. Here, the indium-gallium-zinc-oxide-based photoelectric neuromorphic transistors are fabricated for Morse coding based on spike processing, 405-nm light spikes are used as synaptic inputs, and some essential synaptic plasticity, including excitatory postsynaptic current, short-term plasticity, and high-pass filtering, can be mimicked. More interestingly, Morse codes encoded by light spikes are decoded using our devices and translated into amplitudes. Furthermore, such devices are compatible with standard integrated processes suitable for large-scale integrated neuromorphic systems.
A $dC/dV$ Measurement for Quantum-Dot Light-Emitting Diodes
Jingrui Ma, Haodong Tang, Xiangwei Qu, Guohong Xiang, Siqi Jia, Pai Liu, Kai Wang, and Xiao Wei Sun
Chin. Phys. Lett.    2022, 39 (12): 128401 .   DOI: 10.1088/0256-307X/39/12/128401
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We present $dC/dV$ analysis based on the capacitance-voltage ($C$–$V$) measurement of quantum-dot light-emitting diodes (QLEDs), and find that some key device operating parameters (electrical and optical turn-on voltage, peak capacitance, maximum efficiency) can be directly related to the turning points and maximum/minimum of the $dC/dV$ (versus voltage) curve. By the $dC/dV$ study, the behaviors such as low turn-on voltage, simultaneous electrical and optical turn-on process, and carrier accumulation during the device aging can be well explained. Moreover, we perform the $C$–$V$ and $dC/dV$ measurement of aged devices, and confirm that our $dC/dV$ analysis is correct for them. Thus, our $dC/dV$ analysis method can be applied universally for QLED devices. It provides an in-depth understanding of carrier dynamics in QLEDs through simple $C$–$V$ measurement.
Parallel DNA G-Quadruplex Induced and Stabilized by Curaxin CBL0137
Jing-Wei Kong, Shuo-Xing Dou, Wei Li, Hui Li, and Peng-Ye Wang
Chin. Phys. Lett.    2023, 40 (7): 078701 .   DOI: 10.1088/0256-307X/40/7/078701
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G-quadruplex (G4) is one of the higher-order DNA structures in guanine-rich sequences which are widely distributed across the genome. Due to their presence in oncogenic promoters and telomeres, G4 DNA structures become the novel targets in anticancer drug designs. Curaxin CBL0137, as an important candidate anticancer drug, can effectively inhibit the growth of multiple cancers. Although there is evidence that anticancer activity of curaxin is associated with its ability to bind DNA and to change the DNA topology, its therapeutic target and the underlying anti-cancer mechanism are still unclear. Here we show, for the first time, that curaxin CBL0137 induces G4 folding from anti-parallel to parallel structures, by single-molecule fluorescence resonance energy transfer technique. More importantly, we find that curaxin CBL0137 promotes G4 folding as well as stabilizes the folded G4 structures with long loops, giving a novel insight into effects of curaxin CBL0137 on DNA structures. Our work provides new ideas for the therapeutic mechanism of curaxin CBL0137 and for designs of new G4-targeting anticancer drugs.
Wet Mechanical Milling Induced Phase Transition to Cubic Anti-Perovskite Li$_{2}$OHCl
Di-Xing Ni, Yao-Dong Liu, Zhi Deng, Dian-Cheng Chen, Xin-Xin Zhang, Tao Wang, Shuai Li, and Yu-Sheng Zhao
Chin. Phys. Lett.    2022, 39 (2): 028201 .   DOI: 10.1088/0256-307X/39/2/028201
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Anti-perovskite solid-state electrolyte Li$_{2}$OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature. However, its ionic conductivity increases greatly when the temperature is up to 40 ℃, while it goes through an orthorhombic-to-cubic phase transition. The cubic Li$_{2}$OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10 ℃ by a simple synthesis method of wet mechanical milling. The cubic Li$_{2}$OHCl prepared by this method performs an ionic conductivity of $4.27 \times 10^{-6}$ S/cm at room temperature, about one order of magnitude higher than that of the orthorhombic Li$_{2}$OHCl. The phase-transition temperature is decreased to around 10 ℃. Moreover, it can still remain cubic phase after heat treatment at 210 ℃. This work delivers a huge potential of fabricating high ionic conductivity phase anti-perovskite solid-state electrolyte materials by wet mechanical milling.
Molecular Insights into Striking Antibody Evasion of SARS-CoV-2 Omicron Variant
Zeng-Shuai Yan, Yao Xu, Hong-Ming Ding, and Yu-Qiang Ma
Chin. Phys. Lett.    2022, 39 (10): 108701 .   DOI: 10.1088/0256-307X/39/10/108701
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The SARS-CoV-2 Omicron variant has become the dominant variant in the world. Uncovering the structural basis of altered immune response and enhanced transmission of Omicron is particularly important. Here, taking twenty-five antibodies from four groups as examples, we comprehensively reveal the underlying mechanism of how mutations in Omicron induces the weak neutralization by using molecular simulations. Overall, the binding strength of 68% antibodies is weakened in Omicron, much larger than that in Delta (40%). Specifically, the percentage of the weakened antibodies vary largely in different groups. Moreover, the mutation-induced repulsion is mainly responsive for the weak neutralization in AB/CD groups but does not take effect in EF group. Significantly, we demonstrate that the disappearance of hydrophobic interaction and salt bridges due to residue deletions contributes to the decreased binding energy in NTD group. This work provides unprecedented atomistic details for the distinct neutralization of WT/Delta/Omicron, which informs prospective efforts to design antibodies/vaccines against Omicron.
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