We present and discuss an algorithm to identify and characterize the long icosahedral structures (staggered pentagonal nanowires with 1-5-1-5 atomic structure) that appear in Molecular Dynamics simulations of metallic nanowires of different species subjected to stretching. The use of the algorithm allows the identification of pentagonal rings forming the icosahedral structure as well as the determination of its number, and the maximum length of the pentagonal nanowire. The algorithm is tested with some ideal structures to show its ability to discriminate between pentagonal rings and other ring structures. We applied the algorithm to Ni nanowires with temperatures ranging between 4K and 865K, stretched along the [100] direction. We studied statistically the formation of pentagonal nanowires obtaining the distributions of the maximum length and number of rings as function of the temperature. The pentagonal nanowire maximum length distribution presents a peaked shape, with peaks locate at fixes distances whose separa-tion corresponds to the distance between two consecutive pentagonal rings.
On the role of Sm in solidification of Al-Sm metallic glasses
在Al-Sm金属玻璃凝固过程中，过冷液体原子结构随Sm浓度的增加而逐渐演化为类二十面体团簇。与液体中剩余的团簇相比，这些团簇表现出较慢的动力学，导致增强的无定形相稳定性和玻璃形成能力（GFA）。最大的二十面体排序和原子堆积密度已被发现的Al 90 Sm 10和Al 85 Sm 15合金，分别，而最小的结合能已被发现的Al 93 Sm 7这是一致的组合物的范围内（从Al 92 Sm 8到Al 84 Sm 16）实验发现具有高GFA。
The structural motifs of a Zr$_{50}$Cu$_{45}$Al$_{5}$ metallic glass were learned from atomistic models using a new structure analysis method called motif extraction that employs point-pattern matching and machine learning clustering techniques. The motifs are the nearest-neighbor building blocks of the glass and reveal a well-defined hierarchy of structures as a function of coordination number. Some of the motifs are icosahedral or quasi-icosahedral in structure, while others take on the structure of the most close-packed geometries for each coordination number. These results set the stage fo…
We demonstrate the self-assembled formation of AlN nanowires by molecular beam epitaxy on sputtered TiN films on sapphire. This choice of substrate allows growth at an exceptionally high temperature of 1180 °C. In contrast to previous reports, the nanowires are well separated and do not suffer from pronounced coalescence. This achievement is explained by sufficient Al adatom diffusion on the substrate and the nanowire sidewalls. The high crystalline quality of the nanowires is evidenced by the observation of near band edge emission in the cathodoluminescence spectrum. The key factor for the lo…
We have investigated the photocarrier charge transport in n-type metallic GaAs nanowires (~ 10^17 cm^-3 doping level), grown by hydride vapor phase epitaxy (HVPE) on Si(111) substrates. Analysis of the luminescence intensity spatial profiles for selected energies in the spectrum allows us to determine the spatial distribution of photoelectrons, minority photoholes and electrons of the Fermi sea as a function of distance from the light excitation spot. This analysis shows that charge can be transported over record distances larger than 25 (micro)m at 6K, in spite of the expected localization of…
We have investigated charge and spin transport in n-type metallic GaAs nanowires (~ 10^17 cm^-3 doping level), grown by hydride vapor phase epitaxy (HVPE) on Si substrates. This was done by exciting the nanowire by tightly-focussed circularly-polarized light and by monitoring the intensity and circular polarization spectrum as a function of distance from the excitation spot. The spin-polarized photoelectrons give rise to a well-defined feature in the nearbandgap spectrum, distinct from the main line due to recombination of the spin-unpolarized electrons of the Fermi sea with the same minority …
In the realm of colloidal nanostructures, with its immense capacity for shape and dimensionality control, the form is undoubtedly a driving factor for the tunability of optical and electrical properties in semiconducting or metallic materials. However, influencing the fundamental properties is still challenging and requires sophisticated surface or dimensionality manipulation. In this work, we present such a modification for the example of colloidal lead sulphide nanowires. We show that the electrical properties of lead sulphide nanostructures can be altered from semiconducting to metallic wit…
Pentagonal nanowires from topological crystalline insulators: a platform for intrinsic core-shell nanowires and higher-order topology
International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences（波兰科学院物理研究所磁顶国际研究中心）；Institute for Advanced Study, Shenzhen University（深圳大学高等研究院）；Consiglio Nazionale delle Ricerche (CNR-SPIN), Unitá di Ricerca presso Terzi c/o Universitá “G. D’Annunzio”（意大利国家研究委员会（CNR-SPIN）第泽齐研究单元/阿布鲁佐大学）
The on-going COVID-19 pandemic highlights the severe health risks posed by deep submicron sized airborne viruses and particulates in the spread of infectious diseases. There is an urgent need for the development of efficient, durable and reusable filters for this size range. Here we report the realization of efficient particulate filters using nanowire-based low-density metal foams which combine extremely large surface areas with excellent mechanical properties. The metal foams exhibit outstanding filtration efficiencies (>96.6%) in the PM_{0.3} regime, with potentials for further improvement.…
Intrinsic Resistive Switching in Microtubule-Templated Gold Nanowires for Reconfigurable Nanoelectronics
Helmholtz-Zentrum Dresden-Rossendorf（亥姆霍兹德累斯顿-罗斯多夫中心）；TUD Dresden University of Technology（德累斯顿工业大学）；Max Planck Institute of Molecular Cell Biology and Genetics（马克斯·普朗克分子细胞生物学与遗传学研究所）
While most of the experimental studies are dealing with partially oxidized metallic nanosolids, their behaviour is not well understood theoretically. To this end we utilized molecular dynamics simulation and charge-optimized many-body potential to probe melting of Cu nanoparticles and nanowires with and without a monolayer of Cu$_2$O as a shell. It is shown that partially oxidized nanosolids present a different melting behaviour than the widely accepted picture of melting, and especially different than surface melting. (i) For both types of nanosolids we observed inward diffusion of $\sim$40\%…
采用广义梯度近似赝势密度泛函电子结构计算方法研究了氧化硅纳米线。研究了无限长的直线型和锯齿型Si-O链。还优化了由三维周期性重复的Si 4 O 8单元组成的线，但发现这种结构具有有限的稳定性。计算了这些氧化硅纳米线的几何形状、电子结构和赫希菲尔德电荷。结果表明，Si-O链是金属链，而锯齿链和Si_4O_8纳米线是绝缘体。
Almost three quarters of a century ago, Charles Frank proposed that the deep supercooling observed in metallic liquids is due to icosahedral short-range order (ISRO), which is incompatible with the long-range order of crystal phases. Some evidence in support of this hypothesis has been published previously. However, those studies were based on a small population of maximum supercooling measurements before the onset of crystallization. Here, the results of a systematic statistical study of several hundred maximum supercooling measurements on Ti39.5Zr39.5Ni21 and Zr80Pt20 liquids are presented. …
Electronic structure and magnetic properties of metallocene multiple-decker sandwich nanowires
采用第一性原理方法研究了由3d过渡金属原子（M=Ti to Ni）和金属环（CP）组成的多层夹心纳米线（$CP-M$）的电磁性质.我们用密度泛函理论证明了结构弛豫在决定系统的磁基态中起着重要的作用。值得注意的是，在$CP-Mn$中计算的磁矩为零，而在$CP-V$中，磁矩明显上升。两个化合物显示出半金属铁磁基态$CP-Fe/Cr$，少数/多数自旋通道内具有间隙。为了研究电子关联对$CP-Cr$半金属基态的影响，我们引入了一个简化的三带Hubbard模型，并采用变分集团方法求解.我们讨论的结果作为一个函数的大小的参考集群和强度的平均库仑$U$和交换$J$参数。我们的研究结果表明，对于所研究的参数$U=2-4eV$和$J=0.6-1.2eV$的范围内的半金属字符不保持在本地库仑相互作用的存在下。
FIB synthesis of Bi2Se3 1D nanowires demonstrating the co-existence of Shubnikov-de Haas oscillations and linear magnetoresistance
自从拓扑绝缘体（TI）被发现以来，人们对金属表面态及其对背散射的屏蔽特性以及通过制备纳米器件来研究其纳米尺度下的性质产生了极大的兴趣。在这里，我们解决了一个重要的科学问题，有关TI是否可以清楚地证明拓扑表面状态（TSS）的鲁棒性存在的障碍，不打破任何基本的对称性。FIB研磨的简单直接的方法被用来合成Bi 2Se 3的纳米线，我们认为这是一个有趣的路线来测试TSS的鲁棒性，并获得的结果是新的相比，许多早期的论文在TI的量子传输证明金属SS的镓掺杂的鲁棒性。在垂直磁场作用下，我们观察到了Shubnikov de Haas振荡和线性磁电阻的共存，并对不同沟道长度下的线性磁电阻进行了系统的研究。这里所示的传输特性和估计的物理参数表明SS的制造工具的鲁棒性，触发灵活性，以探索新的奇异量子现象在纳米器件水平。
Development of reliable interatomic potentials is crucial for theoretical studies of relationship between chemical composition, structure and observable properties in glass-forming metallic alloys. Due to ambiguity of potential parametrization procedure, some crucial properties of the system, such as crystallization stability or symmetry of the ground state crystal phase, may not be correctly reproduced in computer simulations. Here we address this issue for ${\rm Cu_{64.5}Zr_{35.5}}$ alloy described by two modifications of embedded atom model potential as well as by \textit{ab initio} molecul…
