Materials Literature
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The magnetic ground state of nanosized systems such as Fe double chains, recently shown to form in the early stages of Fe deposition on Ir(100), is generally nontrivial. Using ab initio density functional theory we find that the straight ferromagnetic (FM) state typical of bulk Fe as well as of isolated Fe chains and…
We propose and analyze a graphene tunneling transit time device based on a heterostructure with a lateral p–i–n junction electrically induced in the graphene layer by the applied gate voltages of different polarity. The depleted i-section of the graphene layer (between the gates) serves as both the tunneling injector…
An effect is considered of alternating (high-frequency) current on the spin-valve-type magnetic junction configuration. The stability with respect to small fluctuations is investigated in the macrospin approximation. When the current frequency is close to the eigenfrequency (precession frequency) of the free layer, pa…
The optically induced oscillatory response of a spherical two-component, shell-core structured, nanoparticle by nodeless elastic vibrations of soft peripheral shell against hard and dynamically immobile inner core is considered. The eigenfrequencies of the even-parity, spheroidal and odd-parity torsional vibrational m…
The transverse acoustic excitation modes were detected by inelastic x-ray scattering in liquid Ga in the Q range above 9 nm(-1) although liquid Ga is mostly described by a hard-sphere liquid. An ab initio molecular dynamics simulation clearly supports this finding. From the detailed analysis for the S(Q,omega) spectra…
We demonstrate a silicon-based high frequency nanomechanical device capable of switching controllably between two states at room temperature. The device uses a nanomechanical resonator with two distinct states in the hysteretic nonlinear regime. In contrast to prior work, we demonstrate room temperature electrostatic…
We present the first angle-resolved photoemission studies of electronic structure in CaC6, a superconducting graphite intercalation compound with T_{c}=11.6 K. We find that, contrary to theoretical models, the electron-phonon coupling on the graphene-derived Fermi sheets with high-frequency graphene-derived phonons is…
We apply interferometric picometrology to measure the complex refractive index and dielectric properties of ultra-thin gold films as a continuous function of thickness from 0.2 nm to 10 nm deposited on thermal oxide on silicon. Three distinct regimes are found for the dielectric constant trajectory in the complex plan…
Magnetic and magnetoelectric excitations in the multiferroic TbMnO3 have been investigated at terahertz frequencies. Using different experimental geometries we can clearly separate the electroactive excitations (electromagnons) from the magnetoactive modes, i.e., antiferromagnetic resonances. Two antiferromagnetic res…
Using state-of-the-art first-principles calculations we study the magnetic behaviour of CeOFeAs. We find the Ce layer moments oriented perpendicular to those of the Fe layers. An analysis of incommensurate magnetic structures reveals that the Ce-Ce magnetic coupling is rather weak with, however, a strong Fe-Ce couplin…
We present in-depth studies of the size tunability and the self-assembly behavior of Janus cylinders possessing a phase segregation into two hemicylinders. The cylinders are prepared by cross-linking the lamella-cylinder morphology of a polystyrene-block-polybutadiene-block-poly(methyl methacrylate) block terpolymer.…
Quantum dots (QDs) are immobilized on the surfaces of magnetic Fe3O4-composite nanospheres (MNSs, see figure). The QDs exhibit intense visible-light emission in fluorescence spectroscopy and successfully facilitate, for the first time, in vivo soft-tissue imaging in live mice. The Fe3O4 nanoparticles respond to an ext…
Cores and effect: Water-dispersible core-shell structures and heterostructures incorporating gold nanocrystals of different shapes (polyhedra, cubes, and rods) and a variety of transition metal sulfide semiconductors (ZnS, CdS, NiS, Ag(2)S, and CuS) are synthesized using cetyltrimethylammonium bromide-encapsulated gol…
Abstract The surface of layered double hydroxide nanoparticles, a potential drug‐delivery nanovehicle, is modified with the cancer‐cell‐specific ligand, folic acid. The surface modification is successfully accomplished through step‐by‐step coupling reactions with aminopropyltriethoxysilane and 1‐ethyl‐3‐(3‐dimethyl am…
Using the concept of "cloning", we report herein a rational approach to grow single-walled carbon nanotubes (SWNTs) with controlled chirality via an open-end growth mechanism. Specifically, by using open-end SWNTs as "seeds/catalysts" (without metal catalysts), "new/duplicate" SWNTs could be grown and cloned from the…
The formation of surface phases on the Si-terminated SiC(0001) surface, from the Si-rich ($3\ifmmode\times\else\texttimes\fi{}3$) structure, through the intermediate ($1\ifmmode\times\else\texttimes\fi{}1$) and $(\sqrt{3}\ifmmode\times\else\texttimes\fi{}\sqrt{3})\ensuremath{-}R30\ifmmode^\circ\else\textdegree\fi{}$ s…
Scanning tunneling microscopy (STM) images taken on a freshly cleaved anatase TiO2(101) sample show an almost perfect surface with very few subsurface impurities and adsorbates. Surface oxygen vacancies are not typically present but can be induced by electron bombardment. In contrast, a reduced anatase (101) crystal s…
A pronounced uniform polar distortion extending over several unit cells enables thin LaAlO3 overlayers on SrTiO3(001) to counteract the charge dipole and thereby neutralize the "polarization catastrophe" that is suggested by simple ion counting. This unanticipated mechanism, obtained from density functional theory cal…
A deoxycholic acid-modified beta-cyclodextrin derivative (2) and an azobenzene-branched poly(acrylic acid) copolymer (3) were prepared, and the association and dissociation of 2 with the trans/cis-azobenzene units in 3 were characterized by UV/vis spectroscopy, induced circular dichroism, and 1H NMR spectroscopy. The…
Resistivity, Seebeck coefficient, and Hall measurements were performed on densified nanocrystalline composite materials of undoped and Ag-doped PbTe nanocrystals to investigate the physical mechanisms responsible for Seebeck coefficient enhancement in nanocrystalline systems. The unique temperature dependence of the r…