Specific Heat of Holmium in Gold and Silver at Low Temperatures
Matthew Herbst, Andreas Reifenberger, Clemens Velte, Holger Dorrer, Christoph E. Düllmann, Christian Enss, Andreas Fleischmann, Loredana Gastaldo, Sebastian Kem… 展开作者
Matthew Herbst, Andreas Reifenberger, Clemens Velte, Holger Dorrer, Christoph E. Düllmann, Christian Enss, Andreas Fleischmann, Loredana Gastaldo, Sebastian Kempf, Tom Kieck, Ulli Köster, Federica Mantegazzini, Klaus Wendt
备注：
15 pages, 4 figures. Replacement with small modifications after peer-review, no change to scientific content
The specific heat of dilute alloys of holmium in gold and in silver plays a major role in the optimization of low temperature microcalorimeters with enclosed $^{163}\textrm{Ho}$, such as the ones developed for the neutrino mass experiment ECHo. We investigate alloys with atomic concentrations of $x_\textrm{Ho}=0.01\,\% - 4\,\%$ at temperatures between $10\,\textrm{mK}$ and $800\,\textrm{mK}$. Due to the large total angular momentum $J=8$ and nuclear spin $I=7/2$ of $\textrm{Ho}^{3+}$ ions, the specific heat of $\underline{\textrm{Au}}\textrm{:Ho}$ and $\underline{\textrm{Ag}}\textrm{:Ho}$ depends on the detailed interplay of various interactions, including contributions from the localized 4f electrons and nuclear contributions via hyperfine splitting. This makes it difficult to accurately determine the specific heat of these materials numerically. Instead, we measure their specific heat by using three experimental set-ups optimized for different concentration and temperature ranges. The results from measurements on six holmium alloys demonstrate that the specific heat of these materials is dominated by a large Schottky anomaly with its maximum at $T\approx 250\,\textrm{mK}$, which we attribute to hyperfine splitting and crystal field interactions. RKKY and dipole-dipole interactions between the holmium atoms cause additional, concentration-dependent effects. With regard to ECHo, we conclude that for typical operating temperatures of $T\leq 20\,\textrm{mK}$, silver holmium alloys with $x_\textrm{Ho}\gtrsim 1\,\%$ are suited best.
Gold nanoparticles (GNPs) constitute a breakthrough in modern chemistry. The recent success in the synthesis and total structure determination of the precise-composition GNPs provides exciting opportunities for fundamental studies and development of novel applications. GNPs allow for specific number of alien metal atoms to be incorporated into the gold core. Doping tunes optical, structural, and electronic properties of the nanostructure. This work examines silver-doped negatively charged Au25Ag25-N (N=1,2,3) GNPs using PM7-MD. GNP is shown to accommodate multiple silver atoms, whereas silver …
Very recent observation of superconductivity in both transport (resistance versus temperature) and magnetization (Zero field cooled) at around 235 K has obviously raised many eyebrows. The experimental fraternity in particular is more thrilled. Although the results presented in the paper are clean and both transport and magnetization measurements do approve the observation of superconductivity to some extent (the shielding fraction is low), the problem is to synthesize or fabricate the material. This I name a goldsmith job, primarily because one has to deal with Gold and Silver nano particles …
A SERS Investigation of Cyanide Adsorption and Reactivity during the Electrodeposition of Gold, Silver and Copper from Aqueous Cyanocomplexes Solutions
We experimentally study the optical second harmonic generation (SHG) from deep subwavelength gold-silver heterodimer and silver-silver and gold-gold homodimers. Our results show that the SHG from the heterodimer is about an order of magnitude more intense. In contrast, calculations based on known theory suggest that it is the silver-silver homodimer that should have the upper hand, putting the present theoretical view at odds with our experimental findings. Following this observation, we propose a dynamic model where nonlinearity emerges not from the material particles themselves but form the …
The interaction between metal atoms and nucleobases has been a topic of high interest due to the wide scientific and technological implications. Combining density functional theory simulations with a literature overview, we achieved an exhaustive study of the ground state electronic properties of DNA/RNA nucleobases interacting with gold and silver atoms at three charge states: neutral, cationic, and anionic. We describe the nature of the stability and electronic properties in each hybrid metallic structure. In addition to the metal interacting with the five isolated nucleobases, we included t…
Metallic colloids are frequently used in industry and provide understanding of science at microns to nanometers scales along with their applicability for various technologically important applications. Present investigations deal morphology-structure of gold, silver and their binary composition while processing the certain amount of their solutions in a newly designed process and tap opportunities of developing tiny shaped particles. At tuned ratio of pulse OFF to ON time and when gold solution was processed, several tiny shaped particles developed at solution surface. Such tiny particles deal…
Gold-Silver (Au-Ag) core-shell nanostructures are gaining importance in stretchable electronics where high tensile and fatigue resistance is of paramount importance. This work proposes the parameterization of a modified embedded atomic model (MEAM) interatomic potential through density functional theory (DFT) calculations for investigating the role of dislocations and defect interaction governing the mechanical behavior of Au-Ag and Ag-Au Core-shell nanostructures under tensile and fatigue loading using molecular dynamics (MD) simulations. A comparative analysis between the Core-shell structur…
This article describes the optical properties of nanostructures composed of silver particles embedded into a gold matrix. In previous studies these materials were shown to exhibit temperature dependent transitions to a highly conductive and strongly diamagnetic state. Here we describe the anomalous optical properties of these nanostructures. Most notably, these materials fail to obey Mie theory and exhibit an unconventional resonance with a maximum at about 4 eV, while the usual gold and silver localized surface plasmon resonances are suppressed. This effect implies a significant deviation fro…
Bimetallic plasmonic nanoparticles enable tuning of the optical response and chemical stability by variation of the composition. The present numerical simulation study compares Ag-Au alloy, Ag@Au core-shell, and Au@Ag core-shell bimetallic plasmonic nanoparticles of both spherical and anisotropic (nanotriangle and nanorods) shapes. By studying both spherical and anisotropic (with LSPR in the near-infrared region) shapes, cases with and without interband transitions of Au can be decoupled. Explicit comparisons are facilitated by numerical models supported by careful validation and examination o…
Transferable 3D Convolutional Neural Networks for Elastic Constants Prediction in Nanoporous Metals
Universidad Carlos III de Madrid（马德里卡洛斯三世大学）；IMDEA Materials Institute（IMDEA材料研究所）；Institute of Mathematics, Polish Academy of Sciences（波兰科学院数学研究所）；Faculty of Mechanical Engineering, Technion-Israel Institute of Technology（以色列理工学院机械工程学院）
Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200, 400, 600 and 700 °C) during a time period of 10 mi…
