592 research outputs found
Normal State Nernst Effect in Electron-doped Pr2-xCexCuO4: Superconducting Fluctuations and Two-band Transport
We report a systematic study of normal state Nernst effect in the
electron-doped cuprates PrCeCuO over a wide range of
doping (0.050.21) and temperature. At low temperatures, we
observed a notable vortex Nernst signal above T in the underdoped films,
but no such normal state vortex Nernst signal is found in the overdoped region.
The superconducting fluctuations in the underdoped region are most likely
incoherent phase fluctuations as found in hole-doped cuprates. At high
temperatures, a large normal state Nernst signal is found at dopings from
slightly underdoped to highly overdoped. Combined with normal state
thermoelectric power, Hall effect and magnetoresistance measurements, the large
Nernst effect is compatible with two-band model. For the highly overdoped
films, the large Nernst effect is anomalous and not explainable with a simple
hole-like Fermi surface seen in photoemission experiments.Comment: 9 pages, 8 figures, accepted in PR
Correlation between incoherent phase fluctuations and disorder in YPrBaCuO epitaxial films from Nernst effect measurements
Measurements of Nernst effect, resistivity and Hall angle on epitaxial films
of YPrBaCuO(Pr-YBCO, 00.4) are
reported over a broad range of temperature and magnetic field. While the Hall
and resistivity data suggest a broad pseudogap regime in accordance with
earlier results, these first measurements of the Nernst effect on Pr-YBCO show
a large signal above the superconducting transition temperature(T). This
effect is attributed to vortex-like excitations in the phase incoherent
condensate existing above T. A correlation between disorder and the width
of the phase fluctuation regime has been established for the YBCO family of
cuprates, which suggests a T110K for disorder-free
YBaCuO.Comment: 5 pages, 6 figure
Spin Susceptibility of the Topological Superconductor UPt3 from Polarized Neutron Diffraction
Experiment and theory indicate that UPt3 is a topological superconductor in
an odd-parity state, based in part from temperature independence of the NMR
Knight shift. However, quasiparticle spin-flip scattering near a surface, where
the Knight shift is measured, might be responsible. We use polarized neutron
scattering to measure the bulk susceptibility with H||c, finding consistency
with the Knight shift but inconsistent with theory for this field orientation.
We infer that neither spin susceptibility nor Knight shift are a reliable
indication of odd-parity
Destruction of Neel order and appearance of superconductivity in electron-doped cuprates by oxygen annealing process
We use thermodynamic and neutron scattering measurements to study the effect
of oxygen annealing on the superconductivity and magnetism in
PrLaCeCuO. Although the transition temperature
measured by susceptibility and superconducting coherence length increase
smoothly with gradual oxygen removal from the annealing process, bulk
superconductivity, marked by a specific heat anomaly at and the presence
of a neutron magnetic resonance, only appears abruptly when is close to
the largest value. These results suggest that the effect of oxygen annealing
must be first determined in order to establish a Ce-doping dependence of
antiferromagnetism and superconductivity phase diagram for electron-doped
copper oxides.Comment: 5 pages, 4 figures, accepted by Phys. Rev.
Recommended from our members
Arsenite binds to the RING finger domains of RNF20-RNF40 histone E3 ubiquitin ligase and inhibits DNA double-strand break repair.
Arsenic is a widespread environmental contaminant. However, the exact molecular mechanisms underlying the carcinogenic effects of arsenic remain incompletely understood. Core histones can be ubiquitinated by RING finger E3 ubiquitin ligases, among which the RNF20-RNF40 heterodimer catalyzes the ubiquitination of histone H2B at lysine 120. This ubiquitination event is important for the formation of open and biochemically accessible chromatin fiber that is conducive for DNA repair. Herein, we found that arsenite could bind directly to the RING finger domains of RNF20 and RNF40 in vitro and in cells, and treatment with arsenite resulted in substantially impaired H2B ubiquitination in multiple cell lines. Exposure to arsenite also diminished the recruitment of BRCA1 and RAD51 to laser-induced DNA double-strand break (DSB) sites, compromised DNA DSB repair in human cells, and rendered cells sensitive toward a radiomimetic agent, neocarzinostatin. Together, the results from the present study revealed, for the first time, that arsenite may exert its carcinogenic effect by targeting cysteine residues in the RING finger domains of histone E3 ubiquitin ligase, thereby altering histone epigenetic mark and compromising DNA DSB repair. Our results also suggest arsenite as a general inhibitor for RING finger E3 ubiquitin ligases
- …