Materials Literature
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In this work, we report direct as well as pulsed electric field-induced resistivity switching and its relaxation in a multiferroic insulator La2NiMnO6. At a fixed base temperature (Tb), the dc resistivity switches abruptly from a high to a low value, which is manifested as an upward jump in the dc current density (J)…
The magnetic properties of a monolayer of Fe4 single molecule magnets grafted onto a Au (111) thin film have been investigated using low energy muon spin rotation. The properties of the monolayer are compared to bulk Fe4. We find that the magnetic properties in the monolayer are consistent with those measured in the b…
We have studied the effect of Fe substitution on magnetic and magnetocaloric properties in La0.7Sr0.3Mn1-xFexO3 (x = 0.05, 0.07, 0.10, 0.15, and 0.20) over a wide temperature range (T = 10-400 K). It is shown that substitution by Fe gradually decreases the ferromagnetic Curie temperature (Tc) and saturation magnetizat…
We predict it is possible to achieve high-efficiency room-temperature spin injection from a mag- netic metal into InAs-based semiconductors using an engineered Schottky barrier based on an InAs/AlSb superlattice. The Schottky barrier with most metals is negative for InAs and positive for AlSb. For such metals there ex…
Fluorescent carbon nanoparticle (CNP) having 2-6 nm in size with quantum yield of about ~3% were synthesized via nitric acid oxidation of carbon soot and this approach can be used for milligram scale synthesis of these water soluble particles. These CNPs are nano-crystalline with predominantly graphitic structure and…
We measure the mechanical thermal noise of soft silicon atomic force microscopy cantilevers. Using an interferometric setup, we have a resolution down to 1E-14 m/rtHz on a wide spectral range (3 Hz to 1E5 Hz). The low frequency behavior depends dramatically on the presence of a reflective coating: almost flat spectrum…
Thin composite films of branched polyethylenimine (BPEI) and Laponite clay platelets were prepared using layer-by-layer assembly. The film thickness was tailored by altering the pH of the aqueous mixtures used to deposit these films, resulting in growth that ranged from 0.5 to 5 nm/bilayer (BL). High-pH BPEI and low-p…
The labeling of cells with fluorescent nanoparticles is promising for various biomedical applications. The objective of this study is to evaluate the biocompatibility and the mechanism of the cellular uptake of fluorescent nanodiamonds (FNDs) in cancer cells (HeLa) and pre-adipocytes (3T3-L1). With flow cytometry and…
Abstract Alle paar Jahre werden neue Stoffklassen mit einzigartigen und faszinierenden Eigenschaften entdeckt. Beispiele aus der jüngeren Vergangenheit sind Hochtemperatur‐Supraleiter und Nanoröhren aus Kohlenstoff. Die jüngste dieser spektakulären Entdeckungen ist Graphen. Graphen weist ungewöhnliche Eigenschaften wi…
A rough hydrophobic surface when immersed in water can result in a "Cassie" state of wetting in which the water is in contact with both the solid surface and the entrapped air. The sustainability of the entrapped air on such surfaces is important for underwater applications such as reduction of flow resistance in micr…
The self-assembly of nanocrystals enables new classes of materials whose properties are controlled by the periodicities of the assembly, as well as by the size, shape and composition of the nanocrystals. While self-assembly of spherical nanoparticles has advanced significantly in the last decade, assembly of rod-shape…
We study by molecular dynamics the interplay between arrest and crystallization in hard spheres. For state points in the plane of volume fraction (0.54 <or= varphi <or= 0.63) and polydispersity (0 <or= s <or= 0.085), we delineate states that spontaneously crystallize from those that do not. For noncrystallizing (or pr…
We have identified the cyclotron resonance response of the purest graphene ever investigated, which can be found in nature on the surface of bulk graphite, in the form of decoupled layers from the substrate material. Probing such flakes with Landau level spectroscopy in the THz range at very low magnetic fields, we de…
Metal nanocrystals are commonly used to mediate important chemical reactions such as water splitting and CO oxidation. To investigate such redox reactions in detail, it would be useful to be able to carry out electrochemistry on single metal nanocrystals. We report here that the surface plasmon resonance of a single g…
Engineering metamaterials with tunable resonances from mid-infrared to near-infrared wavelengths could have far-reaching consequences for chip based optical devices, active filters, modulators, and sensors. Utilizing the metal-insulator phase transition in vanadium oxide (VO(2)), we demonstrate frequency-tunable metam…
Graphene flakes with controlled thicknesses are isolated in solution using density gradient ultracentrifugation. These stable graphene dispersions are produced using the bile salt sodium cholate, which promotes graphite exfoliation and results in graphene-surfactant complexes having buoyant densities that vary with gr…
In many heterogeneous catalysts, the interaction of metal particles with their oxide support can alter the electronic properties of the metal and can play a critical role in determining particle morphology and maintaining dispersion. We used a combination of ultrahigh magnetic field, solid-state magic-angle spinning n…
We quantitatively investigate the size-dependent optical properties of colloidal PbS nanocrystals or quantum dots (Qdots), by combining the Qdot absorbance spectra with detailed elemental analysis of the Qdot suspensions. At high energies, the molar extinction coefficient epsilon increases with the Qdot volume d(3) an…
Every few years, a new material with unique properties emerges and fascinates the scientific community, typical recent examples being high-temperature superconductors and carbon nanotubes. Graphene is the latest sensation with unusual properties, such as half-integer quantum Hall effect and ballistic electron transpor…
This paper describes operational radiation protection issues specific to high-intensity accelerators, aimed at the radiological safety of high-intensity accelerators during construction and operation. The paper is composed of chapters on safety characteristics, radiological safety design and safety management systems…