37,266 research outputs found
Spin transport through a single self-assembled InAs quantum dot with ferromagnetic leads
We have fabricated a lateral double barrier magnetic tunnel junction (MTJ)
which consists of a single self-assembled InAs quantum dot (QD) with
ferromagnetic Co leads. The MTJ shows clear hysteretic tunnel magnetoresistance
(TMR) effect, which is evidence for spin transport through a single
semiconductor QD. The TMR ratio and the curve shapes are varied by changing the
gate voltage.Comment: 4 pages, 3 figure
Properties and Structural Arrangements of the Electrode Material CuDEPP during Energy Storage
Devices for electrical energy storage need to provide high energy yields and output power, guaranteeing at the same time safety, low costs, and long operation times. The porphyrin CuDEPP [5,15‐bis(ethynyl)‐10,20‐diphenylporphinato] copper(II) is a promising electrode material for various battery systems both as anode and cathode. While its functionality has been demonstrated experimentally, there is no atomistic information as to why CuDEPP expresses these interesting properties or how the incorporation of ions affects its structure so far. To answer these questions, CuDEPP is investigated using density functional theory (DFT). Starting with the smallest possible unit (i.e., a single molecule), the spatial dimensionality of the structure is successively increased by studying: 1) di‐ and trimers, 2) molecular stacking in a 1D chain, 3) extending these chains to planar CuDEPP sheets, and finally 4) a three‐dimensionally extended polymer structure. Having thoroughly investigated the isolated properties of the CuDEPP material itself, afterward the insertion (or intercalation) of different ions (including Li, Mg, and Na) is studied, to understand the energetics, diffusion barriers, and structural changes (e.g., volume expansion) within the CuDEPP host material
Tunneling anisotropic magnetoresistance in multilayer-(Co/Pt)/AlOx/Pt structures
We report observations of tunneling anisotropic magnetoresitance (TAMR) in
vertical tunnel devices with a ferromagnetic multilayer-(Co/Pt) electrode and a
non-magnetic Pt counter-electrode separated by an AlOx barrier. In stacks with
the ferromagnetic electrode terminated by a Co film the TAMR magnitude
saturates at 0.15% beyond which it shows only weak dependence on the magnetic
field strength, bias voltage, and temperature. For ferromagnetic electrodes
terminated by two monolayers of Pt we observe order(s) of magnitude enhancement
of the TAMR and a strong dependence on field, temperature and bias. Discussion
of experiments is based on relativistic ab initio calculations of magnetization
orientation dependent densities of states of Co and Co/Pt model systems.Comment: 4 pages, 5 figures, to be published in Phys. Rev. Let
Elastic properties of thin h-BN films investigated by Brillouin light scattering
Hexagonal BN films have been deposited by rf-magnetron sputtering with simultaneous ion plating. The elastic properties of the films grown on silicon substrates under identical coating conditions have been de-termined by Brillouin light scattering from thermally excited surface phonons. Four of the five independent elastic constants of the deposited material are found to be c11 = 65 GPa, c13 = 7 GPa, c33 = 92 GPa and c44 = 53 GPa exhibiting an elastic anisotropy c11/c33 of 0.7. The Young's modulus determined with load indenta-tion is distinctly larger than the corresponding value taken from Brillouin light scattering. This discrepancy is attributed to the specific morphology of the material with nanocrystallites embedded in an amorphous matrix
Thermal decomposition of ethylene on Si(1 1 1): Formation of the Si(1 1 1)√3x √3 carbon structure
Adsorption and thermal decomposition of ethylene on Si(1 1 1) have been studied by photoelectron spectroscopy. The evolution of the C 1s and Si 2p core-levels upon the adsorption of the ethylene and the formation of C-incorporated surfaces by thermal annealing is analyzed, from which the unique chemical and structural properties of √3x √3 reconstructed phase can be derived. We also discuss the coverage of the C atoms involved and their position on the √3x √3 surface in terms of a structure model
Physical Point Simulation in 2+1 Flavor Lattice QCD
We present the results of the physical point simulation in 2+1 flavor lattice
QCD with the nonperturbatively -improved Wilson quark action and the
Iwasaki gauge action at on a
lattice. The physical quark masses together with the lattice
spacing is determined with , and as physical inputs.
There are two key algorithmic ingredients to make possible the direct
simulation at the physical point: One is the mass-preconditioned
domain-decomposed HMC algorithm to reduce the computational cost. The other is
the reweighting technique to adjust the hopping parameters exactly to the
physical point. The physics results include the hadron spectrum, the quark
masses and the pseudoscalar meson decay constants. The renormalization factors
are nonperturbatively evaluated with the Schr{\"o}dinger functional method. The
results are compared with the previous ones obtained by the chiral
extrapolation method.Comment: 20 pages, 17 figures, version to appear in Phys. Rev.
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