Materials Literature
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We investigate the electron transport properties of a model magnetic molecule formed by two magnetic centers whose exchange coupling can be altered with a longitudinal electric field. In general we find a negative differential conductance at low temperatures originating from the different scattering amplitudes of the…
We have calculated the chemical trend of magnetic exchange parameters (${J}_{dd}$, $N\ensuremath{\alpha}$, and $N\ensuremath{\beta}$) of Zn-based II-VI semiconductors $\text{Zn}A$ ($A=\text{O}$, S, Se, and Te) doped with Co or Mn. We show that a proper treatment of electron correlations by the local spin-density appro…
The molecule-based magnet [Ru$_2$(O$_2$CMe)$_4$]$_3$[Cr(CN)$_6$] contains two weakly-coupled, interpenetrating sublattices in a body-centered cubic structure. Although the field-dependent magnetization indicates a metamagnetic transition from an antiferromagnet to a paramagnet, the hysteresis loop also exhibits a subs…
Ultrasmall copper nanoparticles are produced by N,N,N',N'-tetramethyl-p-phenylenediamine (TMPDA) reduction of aqueous Cu(2+) on a hydrophobically immobilized sodium dodecylbenzenesulfonate (SDBS) surfactant template in the presence of sodium citrate at room temperature. Single-walled carbon nanotubes (SWNTs) act as a…
We studied the entropy change and the shift of the martensitic transformation temperatures with magnetic field in samples of a polycrystalline Ni–Co–Mn–In alloy having different degrees of long-range atomic order due to different heat treatments. We found, for the samples of the same composition, strong variations of…
Using micron-sized Hall sensor arrays to obtain time-resolved measurements of the local magnetization, we report a systematic study in the molecular magnet ${\text{Mn}}_{12}$ acetate of magnetic avalanches controllably triggered in different fixed external magnetic fields and for different values of the initial magnet…
Mn 5 Ge 3 C x films with x≥0.5 were experimentally shown to exhibit a strongly enhanced Curie temperature TC compared to Mn5Ge3. In this letter we present the results of our first principles calculations within Green’s function approach, focusing on the effect of carbon doping on the electronic and magnetic properties…
We examine the appearance of a spin-density wave in the FeAs parent compounds due to an excitonic instability. Using a realistic four-band model, we show that the magnetic state depends very sensitively on the details of the band structure. We demonstrate that an orthorhombic distortion of the crystal enhances the sta…
Strain has a crucial effect on the optical and electronic properties of nanostructures. We calculate the atomistic strain distribution in silicon nanocrystals up to a diameter of 3.2 nm embedded in an amorphous silicon dioxide matrix. A seemingly conflicting picture arises when the strain field is expressed in terms o…
In this letter, the authors present a study of the energetics and magnetic interactions in Fe doped ZnO clusters by ab initio density functional calculations. The results indicate that defects under suitable conditions can induce ferromagnetic interactions between the dopant Fe atoms whereas antiferromagnetic coupling…
With the increase of the lattice distortion, the orthorhombic manganites $R$MnO$_3$ ($R$$=$ La, Pr, Nd, Tb, and Ho) are known to undergo the phase transition from the layered A-type antiferromagnetic (AFM) state to the zigzag E-type AFM state. We consider the microscopic origin of this transition. Our approach consist…
We report a kinetically controlled approach to synthesizing thiolate-capped 20-atom gold clusters. ESI mass spectrometry analysis in combination with other methods, including elemental analysis, XPS, NMR, and thermogravimetric analysis, determines the cluster composition to be Au(20)(SCH(2)CH(2)Ph)(16). The Au(20)(SCH…
We describe an easy method of improving the promising hydrogen storage capabilities of hydrazine borane by adding an equimolar amount of lithium hydride. The resulting mixture contains 14.8 wt % H(2). The hydrogen release behavior of both the pure hydrazine borane and the LiH mixture was studied at various temperature…
On again, off again: A pyrene-based covalent organic framework (see structure: blue pyrene, white B, red O) facilitates exciton migration and carrier transportation, harvests visible-light photons, and responds quickly to irradiation with light to enable the generation of a significant photocurrent. The framework is c…
Strongly luminescent CuInS 2 /ZnS core/shell nanocrystals were synthesized from copper iodide, indium acetate, zinc stearate, and dodecanethiol as starting compounds in octadecene solvent. The as-prepared core/shell nanocrystals exhibit a low size distribution (<10%), and present photoluminescence in the range of 550−…
Some of pathogenic and food spoilage bacteria can attach on food contact surfaces and form a biofilm, the source of contamination of foods. Biofilm is a functional consortium of microorganisms attached to the surface and is embedded in the extracellular polymeric substances (EPS) produced by the microorganisms. Biofil…
A first order structural Jahn-Teller transition at T_{JT} = 650 K has been recently reported for the quadruple perovskite LaMn7O12 . We have carried out magnetization and transport measurements below and above T_{JT} in order to investigate the effect of the transition. Electrical conduction turns out to be polaronic,…
Metamaterials have significantly extended the range of electromagnetic properties available to device designers. An interesting application of these new materials is to the problem of cloaking, where the goal is to render an object invisible to electromagnetic radiation within a certain frequency range. Here, I review…
Abstract This paper reviews major techniques of aligning carbon nanotubes, either during the growth or by the post-growth processing. A number of post-processing alignment techniques are discussed, which employ mechanical stretching, fracture, compression, friction, filtration, fiber drawing, gas flow, liquid crystals…
Classical molecular dynamics simulation with embedded atom method potential had been performed to investigate the surface structure and solidification morphology of aluminum nanoclusters Aln (n = 256, 604, 1220 and 2048). It is found that Al cluster surfaces are comprised of (111) and (001) crystal planes. (110) cryst…