Nano Letters最新文献

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Significant Power Consumption Reduction and Speed Boosting in Phase Change Memory with Nanocurrent Channels 利用纳米电流通道大幅降低相变存储器功耗并提高速度

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03900

Yuntao Zeng, Ge Ma, Han Li, Xiaomin Cheng, Xiangshui Miao

The excessive power consumption is challenging for phase change memory (PCM) on its way to becoming universal memory in complex hierarchies of memory systems. Here, from the perspective of device structure, by adding a nanocurrent-channel (NCC) layer between the electrode layer and phase change layer, a RESET power consumption reduction by more than 95% and 10 times faster SET speed were realized simultaneously. Through the first principle calculations, Au and SiO₂ were screened as the metal and insulating matrix material of NCC layer, respectively. Our PCM device with a Au-SiO₂ NCC layer shows an ultralow RESET power consumption, down to 381 fJ, and an ultrafast SET speed (8 ns). Much higher current density near NCC in the phase change layer and thermal barrier effect of insulating matrix material were confirmed by finite element analysis (FEA), and the role of Au nanochannels was revealed by transmission electron microscopy (TEM). Our NCC layer structure provides a simple and practicable method to significantly decrease PCM power consumption.

在复杂的分层存储器系统中，相变存储器（PCM）在成为通用存储器的道路上面临着功耗过高的挑战。本文从器件结构的角度出发，通过在电极层和相变层之间添加纳米电流通道（NCC）层，同时实现了 RESET 功耗降低 95% 以上和 SET 速度提高 10 倍的目标。通过第一原理计算，筛选出金和二氧化硅分别作为 NCC 层的金属和绝缘基体材料。采用金-二氧化硅 NCC 层的 PCM 器件具有超低的 RESET 功耗（低至 381 fJ）和超快的 SET 速度（8 ns）。有限元分析（FEA）证实了相变层中 NCC 附近更高的电流密度和绝缘基体材料的热障效应，透射电子显微镜（TEM）揭示了金纳米通道的作用。我们的 NCC 层结构为大幅降低 PCM 功耗提供了一种简单实用的方法。

引用次数: 0

Enhanced Superconductivity of Hydrogenated β12 Borophene 氢化 β12 硼吩超导电性的增强

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03845

Božidar N. Šoškić, Jonas Bekaert, Cem Sevik, Milorad V. Milošević

Borophene stands out among elemental two-dimensional materials due to its extraordinary physical properties, including structural polymorphism, strong anisotropy, metallicity, and the potential for phonon-mediated superconductivity. However, confirming superconductivity in borophene experimentally has been evasive to date, mainly due to the detrimental effects of metallic substrates and its susceptibility to oxidation. In this study, we present an ab initio analysis of superconductivity in the experimentally synthesized hydrogenated β₁₂ borophene, which has been proven to be less prone to oxidation. Our findings demonstrate that hydrogenation significantly enhances both the stability and superconducting properties of β₁₂ borophene. Furthermore, we reveal that tensile strain and hole doping, achievable through various experimental methods, significantly enhance the critical temperature, reaching up to 29 K. These findings not only promote further fundamental research on superconducting borophene and its heterostructures, but also position hydrogenated borophene as a versatile platform for low-dimensional superconducting electronics.

硼吩因其非凡的物理特性，包括结构多态性、强各向异性、金属性和声子介导超导潜力，在元素二维材料中脱颖而出。然而，主要由于金属基底的不利影响及其易氧化性，迄今为止，硼吩中超导电性的实验证实一直遥遥无期。在本研究中，我们对实验合成的氢化 β12 硼吩中的超导性进行了ab initio 分析。我们的研究结果表明，氢化能显著增强 β12 硼吩的稳定性和超导特性。此外，我们还发现，通过各种实验方法实现的拉伸应变和空穴掺杂可显著提高临界温度，最高可达 29 K。这些发现不仅促进了对超导硼吩和其异质结构的进一步基础研究，还将氢化硼吩定位于低维超导电子学的多功能平台。

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引用次数: 0

ChiSCAT: Unsupervised Learning of Recurrent Cellular Micromotion Patterns from a Chaotic Speckle Pattern ChiSCAT：从混沌斑点模式中无监督学习递归细胞微动模式

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c02425

Andrii Trelin, Sophie Kussauer, Paul Weinbrenner, Anja Clasen, Robert David, Christian Rimmbach, Friedemann Reinhard

There is considerable evidence that action potentials are accompanied by “intrinsic optical signals”, such as a nanometer-scale motion of the cell membrane. Here we present ChiSCAT, a technically simple imaging scheme that detects such signals with interferometric sensitivity. ChiSCAT combines illumination by a chaotic speckle pattern and interferometric scattering microscopy (iSCAT) to sensitively detect motion in any direction. The technique features reflective high-NA illumination, common-path suppression of vibrations, and a large field of view. This approach maximizes sensitivity to motion, but does not produce a visually interpretable image. We show that unsupervised learning based on matched filtering and motif discovery can recover underlying motion patterns and detect action potentials. We demonstrate these claims in an experiment on blebbistatin-paralyzed cardiomyocytes. ChiSCAT opens the door to action potential measurement in scattering tissue, including a living brain.

有大量证据表明，动作电位伴随着 "内在光学信号"，如细胞膜纳米级的运动。我们在此介绍一种技术简单的成像方案--ChiSCAT，它能以干涉灵敏度检测此类信号。ChiSCAT 结合了混沌斑点模式照明和干涉散射显微技术（iSCAT），可灵敏地检测任何方向的运动。该技术的特点是反射式高 NA 照明、共径振动抑制和大视场。这种方法能最大限度地提高对运动的灵敏度，但不能生成可视化解释的图像。我们的研究表明，基于匹配过滤和图案发现的无监督学习可以恢复潜在的运动模式并检测动作电位。我们在一项关于溴必司汀麻痹的心肌细胞的实验中证明了这些说法。ChiSCAT 为在散射组织（包括活体大脑）中测量动作电位打开了大门。

引用次数: 0

Biomass Hydrogel Electrolytes toward Green and Durable Supercapacitors: Enhancing Flame Retardancy, Low-Temperature Self-Healing, Self-Adhesion, and Long-Term Cycling Stability 面向绿色耐用超级电容器的生物质水凝胶电解质：增强阻燃性、低温自愈性、自粘性和长期循环稳定性

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c02852

Nannan Zhu, Qijin Teng, Yibin Xing, Xiyao Wang, Zuocai Zhang, Xuejuan Wan

Hydrogels have shown promise as quasi-solid-state electrolytes for flexible supercapacitors but face challenges such as poor self-repair, unstable electrode adhesion, limited temperature range, and flammability. Herein, an all-round green hydrogel electrolyte (silk nanofibers (SNFs)/peach gum polysaccharide (PGP)/borax/glycerol (SPBG)-ZnSO₄) addresses these issues through dynamic cross-linking of peach gum polysaccharide and silk nanofibers with borax, integrating varieties of key property including high water retention, broad temperature tolerance (−20 to 90 °C), excellent self-adhesion (60.7 kPa for carbon cloth electrodes), satisfactory flame retardancy (limited oxygen index of 51%), low-temperature self-healing (−20 °C), and good ionic conductivity (7.68 mS cm^–1). The resulting supercapacitor exhibits excellent cycling stability with 98.2% capacitance retention after 40,000 long cycles at 25 °C. The specific capacitance retention remains above 90% even after 15,000 cycles at high/low temperatures (50 °C/–20 °C). Furthermore, the flexible supercapacitor demonstrates stable performance under mechanical stimuli (180° bending and perforation), highlighting the potential of biomass hydrogels in flexible energy storage devices.

水凝胶有望成为柔性超级电容器的准固态电解质，但也面临着自我修复能力差、电极附着力不稳定、温度范围有限以及易燃性等挑战。在此，一种全方位的绿色水凝胶电解质（蚕丝纳米纤维（SNFs）/桃胶多糖（PGP）/硼砂/甘油（SPBG）-ZnSO4）通过桃胶多糖和蚕丝纳米纤维与硼砂的动态交联解决了这些问题，集成了多种关键特性，包括高保水、宽温度耐受性（-20 至 90 °C）、优异的自粘性（碳布电极为 60.7 kPa）、令人满意的阻燃性（有限氧指数为 51%）、低温自愈性（-20 °C）和良好的离子导电性（7.68 mS cm-1）。所制成的超级电容器具有出色的循环稳定性，在 25 °C 下经过 40,000 次长循环后，电容保持率为 98.2%。即使在高温/低温（50 °C/-20 °C）条件下循环 15,000 次，比电容保持率仍能保持在 90% 以上。此外，这种柔性超级电容器在机械刺激（180°弯曲和穿孔）下也表现出稳定的性能，凸显了生物质水凝胶在柔性储能设备中的潜力。

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引用次数: 0

Imaging Spectropolarimeter Using a Multifunctional Metasurface 使用多功能元表面的成像光谱仪

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03787

Li Chen, Yu Yu, Xinliang Zhang

Spectral polarization imaging is critical for broad applications ranging from remote sensing to biomedicine. Here, we propose and experimentally demonstrate an imaging spectropolarimeter based on a single multifunctional metasurface. The designed metasurface accurately maps spectral and polarization information onto focal points and vortex beams, enabling simultaneous detection through intensity distributions. More specifically, spectral detection is achieved by determining the azimuthal angle of the strongest focal point, while polarization detection is accomplished by synthesizing the intensity of focal points and the interference pattern of output vortex beams. Experimental results indicate the successful reconstruction for six discrete wavelengths, with the average relative polarization error ranging from 7.85% to 13%. Additionally, the metasurface exhibits excellent imaging and edge detection capabilities owing to the focusing properties and the generation of vortex beams, achieving an imaging resolution of up to 1.4-fold wavelength and offering a new solution for a wide range of applications.

光谱偏振成像对于从遥感到生物医学的广泛应用至关重要。在此，我们提出并通过实验演示了一种基于单一多功能元表面的成像光谱偏振计。所设计的元表面可将光谱和偏振信息准确映射到焦点和涡流束上，从而通过强度分布实现同步检测。更具体地说，光谱检测是通过确定最强焦点的方位角来实现的，而偏振检测则是通过合成焦点的强度和输出涡流束的干涉模式来实现的。实验结果表明，成功重建了六个离散波长，平均相对偏振误差在 7.85% 到 13% 之间。此外，由于聚焦特性和漩涡光束的产生，元表面显示出卓越的成像和边缘检测能力，实现了高达 1.4 倍波长的成像分辨率，为广泛的应用提供了新的解决方案。

引用次数: 0

Electron Collimation in Twisted Bilayer Graphene via Gate-Defined Moiré Barriers 通过栅极定义的 Moiré 屏障实现双层石墨烯扭转中的电子准直

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03373

Wei Ren, Xi Zhang, Ziyan Zhu, Moosa Khan, Kenji Watanabe, Takashi Taniguchi, Efthimios Kaxiras, Mitchell Luskin, Ke Wang

Electron collimation via a graphene p–n junction allows electrostatic control of ballistic electron trajectories akin to that of an optical circuit. Similar manipulation of novel correlated electronic phases in twisted-bilayer graphene (tBLG) can provide additional probes to the underlying physics and device components toward advanced quantum electronics. In this work, we demonstrate collimation of the electron flow via gate-defined moiré barriers in a tBLG device, utilizing the band-insulator gap of the moiré superlattice. A single junction can be tuned to host a chosen combination of conventional pseudo barrier and moiré tunnel barriers, from which we demonstrate improved collimation efficiency. By measuring transport through two consecutive moiré collimators separated by 1 μm, we demonstrate evidence of electron collimation in tBLG in the presence of realistic twist-angle inhomogeneity.

通过石墨烯 p-n 结的电子准直，可以对弹道电子轨迹进行类似光路的静电控制。对扭曲双层石墨烯（tBLG）中的新型相关电子相位进行类似操作，可以为实现先进量子电子学的基础物理学和器件组件提供额外的探针。在这项工作中，我们利用摩尔纹超晶格的带绝缘体间隙，在 tBLG 器件中通过栅极定义的摩尔纹势垒演示了电子流的准直化。我们可以调整单个结，使其容纳所选的传统伪势垒和摩尔纹隧道势垒组合，从而提高准直效率。通过测量通过两个相距 1 μm 的连续莫伊里准直器的传输，我们证明了 tBLG 在现实扭曲角不均匀性情况下的电子准直。

引用次数: 0

Nanoscale Operando Imaging of Electrically Driven Charge-Density Wave Phase Transitions. 电驱动电荷密度波相变的纳米级操作成像。

IF 9.6 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03324

Till Domröse, Noelia Fernandez, Christian Eckel, Kai Rossnagel, R Thomas Weitz, Claus Ropers

Structural transformations in strongly correlated materials promise efficient and fast control of materials' properties via electrical or optical stimulation. The desired functionality of devices operating based on phase transitions, however, will also be influenced by nanoscale heterogeneity. Experimentally characterizing the relationship between microstructure and phase switching remains challenging, as nanometer resolution and high sensitivity to subtle structural modifications are required. Here, we demonstrate nanoimaging of a current-induced phase transformation in the charge-density wave (CDW) material 1T-TaS₂. Combining electrical characterizations with tailored contrast enhancement, we correlate macroscopic resistance changes with the nanoscale nucleation and growth of CDW phase domains. In particular, we locally determine the transformation barrier in the presence of dislocations and strain, underlining their non-negligible impact on future functional devices. Thereby, our results demonstrate the merit of tailored contrast enhancement and beam shaping for advanced operando microscopy of quantum materials and devices.

强相关材料的结构转变有望通过电刺激或光刺激对材料特性进行高效快速的控制。然而，基于相变运行的设备所需的功能也会受到纳米级异质性的影响。实验表征微观结构与相变之间的关系仍然具有挑战性，因为需要纳米分辨率和对微妙结构变化的高灵敏度。在这里，我们展示了电荷密度波（CDW）材料 1T-TaS2 中电流诱导相变的纳米成像。结合电学表征和定制对比度增强，我们将宏观电阻变化与 CDW 相域的纳米级成核和生长联系起来。特别是，我们在局部确定了位错和应变存在时的转化障碍，强调了它们对未来功能器件不可忽视的影响。因此，我们的研究结果证明了量子材料和器件高级操作显微镜的定制对比度增强和光束整形的优点。

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引用次数: 0

Epitaxial Growth of Large-Scale α-Phase Antimonene 大规模α相锑的外延生长

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03277

Tomasz Jaroch, Lucyna Żurawek-Wyczesany, Agnieszka Stȩpniak-Dybala, Mariusz Krawiec, Marek Kopciuszyński, Piotr Dróżdż, Mariusz Gołȩbiowski, Ryszard Zdyb

Two-dimensional materials composed of elements from the 15th group of the periodic table remain largely unexplored. The primary challenge in advancing this research is the lack of large-scale layers that would facilitate extensive studies using laterally averaging techniques and enable functionalization for the fabrication of novel electronic, optoelectronic, and spintronic devices. In this report, we present a method for synthesizing large-scale antimonene layers, on the order of cm². By employing molecular beam epitaxy, we successfully grow a monolayer film of α-phase antimonene on a W(110) surface passivated with a single-atom-thick layer of Sb atoms. The formation of α phase antimonene is confirmed through scanning tunneling microscopy and low-energy electron diffraction measurements. The isolated nature of the α-phase is further evidenced in the electronic structure, with linearly dispersed bands observed through angle-resolved photoelectron spectroscopy and supported by ab initio calculations.

由元素周期表第 15 族元素组成的二维材料在很大程度上仍未得到探索。推进这项研究的主要挑战是缺乏大尺度的层，而这种大尺度的层有助于使用横向平均技术进行广泛的研究，并能为制造新型电子、光电和自旋电子器件进行功能化。在本报告中，我们介绍了一种合成大尺度锑层的方法，其尺寸约为 cm2。通过采用分子束外延技术，我们成功地在用单原子厚的锑原子层钝化的 W(110) 表面上生长出单层的 α 相锑烯薄膜。扫描隧道显微镜和低能电子衍射测量证实了 α 相锑烯的形成。电子结构进一步证明了 α 相的孤立性，通过角度分辨光电子能谱观察到了线性分散带，并得到了 ab initio 计算的支持。

引用次数: 0

Engineering Carrier Density and Effective Mass of Plasmonic TiN Films by Tailoring Nitrogen Vacancies. 通过调整氮空位来控制等离子体 TiN 薄膜的载流子密度和有效质量。

IF 9.6 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c03534

Shunda Zhang, Tian-Yu Sun, Zhen Wang, Ruyi Zhang, Yu Lin, Shaozhu Xiao, Guanhua Su, Jiachang Bi, Peiyi Li, Hongliang Zhang, Lingyan Liang, Fang Yang, Qinghua Zhang, Liang-Feng Huang, Yanwei Cao

The introduction of nitrogen vacancies has been shown to be an effective way to tune the plasmonic properties of refractory titanium nitrides. However, its underlying mechanism remains debated due to the lack of high-quality single-crystalline samples and a deep understanding of electronic properties. Here, a series of epitaxial titanium nitride films with varying nitrogen vacancy concentrations (TiN_x) were synthesized. Spectroscopic ellipsometry measurements revealed that the plasmon energy could be tuned from 2.64 eV in stoichiometric TiN to 3.38 eV in substoichiometric TiN_x. Our comprehensive analysis of electrical and plasmonic properties showed that both the increased electronic states around the Fermi level and the decreased carrier effective mass due to the modified electronic band structures are responsible for tuning the plasmonic properties of TiN_x. Our findings offer a deeper understanding of the tunable plasmonic properties in epitaxial TiN_x films and are beneficial for the development of nitride plasmonic devices.

引入氮空位已被证明是调整难熔氮化钛等离子特性的有效方法。然而，由于缺乏高质量的单晶样品和对电子特性的深入了解，其基本机制仍存在争议。在此，我们合成了一系列氮空位浓度不同的氮化钛外延薄膜（TiNx）。光谱椭偏仪测量结果表明，等离子体能量可从化学计量氮化钛的 2.64 eV 调整到亚化学计量氮化钛的 3.38 eV。我们对电学和等离子特性的综合分析表明，费米级附近电子状态的增加和电子带结构的改变导致载流子有效质量的降低是调整 TiNx 等离子特性的原因。我们的研究结果加深了对 TiNx 外延薄膜可调等离子特性的理解，有利于氮化物等离子器件的开发。

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引用次数: 0

Topological Surface State Evolution in Bi2Se3 via Surface Etching 通过表面蚀刻实现 Bi2Se3 中拓扑表面态的演变

IF 10.8 1区材料科学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Nano Letters

Pub Date : 2024-09-24 DOI: 10.1021/acs.nanolett.4c02846

Ziqin Yue, Jianwei Huang, Ruohan Wang, Jia-Wan Li, Hongtao Rong, Yucheng Guo, Han Wu, Yichen Zhang, Junichiro Kono, Xingjiang Zhou, Yusheng Hou, Ruqian Wu, Ming Yi

Topological insulators are materials that have an insulating bulk interior while maintaining gapless boundary states against back scattering. Bi₂Se₃ is a prototypical topological insulator with a Dirac-cone surface state around Γ. Here, we present a controlled methodology to gradually remove Se atoms from the surface Se–Bi–Se–Bi–Se quintuple layers, eventually forming bilayer-Bi on top of the quintuple bulk. Our method allows us to track the topological surface state and confirm its robustness throughout the surface modification. Importantly, we report a relocation of the topological Dirac cone in both real space and momentum space as the top surface layer transitions from quintuple Se–Bi–Se–Bi–Se to bilayer-Bi. Additionally, charge transfer among the different surface layers is identified. Our study provides a precise method to manipulate surface configurations, allowing for the fine-tuning of the topological surface states in Bi₂Se₃, which represents a significant advancement toward nanoengineering of topological states.

拓扑绝缘体是一种具有绝缘体内部，同时保持无间隙边界态以对抗反向散射的材料。Bi2Se3 是一种典型的拓扑绝缘体，在 Γ 附近具有狄拉克锥表面态。在这里，我们提出了一种可控方法，从表面 Se-Bi-Se-Bi-Se 五重层中逐渐移除 Se 原子，最终在五重体顶部形成双层 Bi。通过我们的方法，我们可以跟踪拓扑表面状态，并确认其在整个表面改性过程中的稳健性。重要的是，我们报告了拓扑狄拉克锥在实空间和动量空间的迁移情况，即顶部表层从五重硒-铋-硒-铋-硒过渡到双层铋。此外，我们还发现了不同表层之间的电荷转移。我们的研究提供了操纵表面构型的精确方法，允许对 Bi2Se3 的拓扑表面状态进行微调，这代表了拓扑状态纳米工程的重大进展。

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引用次数: 0

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