15,000 research outputs found
Pumped spin-current and shot noise spectra in a single quantum dot
We exploit the pumped spin-current and current noise spectra under
equilibrium condition in a single quantum dot connected to two normal leads, as
an electrical scheme for detection of the electron spin resonance (ESR) and
decoherence. We propose spin-resolved quantum rate equations with correlation
functions in Laplace-space for the analytical derivation of the zero-frequency
atuo- and cross-shot noise spectra of charge- and spin-current. Our results
show that in the strong Coulomb blockade regime, ESR-induced spin flip
generates a finite spin-current and the quantum partition noises in the absence
of net charge transport. Moreover, spin shot noise is closely related to the
magnetic Rabi frequency and decoherence and would be a sensitive tool to
measure them.Comment: 4 pages, 3 figures, to be published in Phys. Rev. Lette
Spin Hall effect in infinitely large and finite-size diffusive Rashba two-dimensional electron systems: A helicity-basis nonequilibrium Green's function approach
A nonequilibrium Green's function approach is employed to investigate the
spin-Hall effect in diffusive two-dimensional electron systems with Rashba
spin-orbit interaction. Considering a long-range electron-impurity scattering
potential in the self-consistent Born approximation, we find that the spin-Hall
effect arises from two distinct interband polarizations in helicity basis: a
disorder-unrelated polarization directly induced by the electric field and a
polarization mediated by electron-impurity scattering. The disorder-unrelated
polarization is associated with all electron states below the Fermi surface and
produces the original intrinsic spin-Hall current, while the disorder-mediated
polarization emerges with contribution from the electron states near the Fermi
surface and gives rise to an additional contribution to the spin-Hall current.
Within the diffusive regime, the total spin-Hall conductivity vanishes in {\it
infinitely large} samples, independently of temperature, of the spin-orbit
coupling constant, of the impurity density, and of the specific form of the
electron-impurity scattering potential. However, in a {\it finite-size} Rashba
two-dimensional semiconductor, the spin-Hall conductivity no longer always
vanishes. Depending on the sample size in the micrometer range, it can be
positive, zero or negative with a maximum absolute value reaching as large as
order of magnitude at low temperatures. As the sample size increases,
the total spin-Hall conductivity oscillates with a decreasing amplitude. We
also discuss the temperature dependence of the spin-Hall conductivity for
different sample sizes.Comment: 9 pages, 3 figures, extended version of cond-mat/041162
Template epitaxial growth of thermoelectric Bi/BiSb superlattice nanowires by charge-controlled pulse electrodeposition
© The Electrochemical Society, Inc. 2009. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in The Journal of The Electrochemical Society, 156(9), 2009.Bi/BiSb superlattice nanowires (SLNWs) with a controllable and very small bilayer thickness and a sharp segment interface were grown by adopting a charge-controlled pulse electrodeposition. The deposition parameters were optimized to ensure an epitaxial growth of the SLNWs with a preferential orientation. The segment length and bilayer thickness of the SLNWs can be controlled simply by changing the modulating time, and the consistency of the segment length can be well maintained by our approach. The Bravais law in the electrodeposited nanowires is verified by the SLNW structure. The current–voltage measurement shows that the SLNWs have good electrical conductance, particularly those with a smaller bilayer thickness. The Bi/BiSb SLNWs might have excellent thermoelectric performances.National Natural Science Foundation
of China and the National
Major Project of Fundamental Research for Nanomaterials and
Nanostructures
KDM2B/FBXL10 targets c-Fos for ubiquitylation and degradation in response to mitogenic stimulation.
KDM2B (also known as FBXL10) controls stem cell self-renewal, somatic cell reprogramming and senescence, and tumorigenesis. KDM2B contains multiple functional domains, including a JmjC domain that catalyzes H3K36 demethylation and a CxxC zinc-finger that recognizes CpG islands and recruits the polycomb repressive complex 1. Here, we report that KDM2B, via its F-box domain, functions as a subunit of the CUL1-RING ubiquitin ligase (CRL1/SCF(KDM2B)) complex. KDM2B targets c-Fos for polyubiquitylation and regulates c-Fos protein levels. Unlike the phosphorylation of other SCF (SKP1-CUL1-F-box)/CRL1 substrates that promotes substrates binding to F-box, epidermal growth factor (EGF)-induced c-Fos S374 phosphorylation dissociates c-Fos from KDM2B and stabilizes c-Fos protein. Non-phosphorylatable and phosphomimetic mutations at S374 result in c-Fos protein which cannot be induced by EGF or accumulates constitutively and lead to decreased or increased cell proliferation, respectively. Multiple tumor-derived KDM2B mutations impaired the function of KDM2B to target c-Fos degradation and to suppress cell proliferation. These results reveal a novel function of KDM2B in the negative regulation of cell proliferation by assembling an E3 ligase to targeting c-Fos protein degradation that is antagonized by mitogenic stimulations
Two-dimensional Superconductivity from Dimerization of Atomically Ordered AuTe2Se4/3 Cubes
The emergent phenomena such as superconductivity and topological phase
transitions can be observed in strict two-dimensional crystalline matters.
Artificial interfaces and one atomic thickness layers are typical 2D materials
of this kind. Although having 2D characters, most bulky layered compounds,
however, do not possess these striking properties. Here, we report the 2D
superconductivity in bulky AuTe2Se4/3,where the reduction in dimensionality is
achieved through inducing the elongated covalent Te-Te bonds. The
atomic-resolution images reveal that the Au, Te and Se are atomically ordered
in a cube, among which are Te-Te bonds of 3.18 A and 3.28 A. The
superconductivity at 2.85 K is discovered, which is unraveled to be the
quasi-2D nature owing to the BKT topological transition. The nesting of nearly
parallel Fermi sheets could give rise to strong electron-phonon coupling. It is
proposed to further depleting the thickness could result in more
topologically-related phenomena.Comment: 16 pages, 5 figures,To be published in Nature Communication
-meson in nuclear matter
The -nucleon (N) interactions are deduced from the heavy baryon
chiral perturbation theory up to the next-to-leading-order terms. Combining the
relativistic mean-field theory for nucleon system, we have studied the
in-medium properties of -meson. We find that all the elastic scattering
N interactions come from the next-to-leading-order terms. The N
sigma term is found to be about 280130 MeV. The off-shell terms are also
important to the in-medium properties of -meson. On application of the
latest determination of the N scattering length, the ratio of
-meson effective mass to its vacuum value is near , while
the optical potential is about MeV, at the normal nuclear density.Comment: 8 pages, 3 figures, to appear in PRC, many modification
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