387 research outputs found
Effect of stripe order strength for the Nernst effect in La_{2-x}Sr_xCu_4 single crystals
We have precisely measured the Nernst effect in Nd-doped
LaSrCuO single crystals with controlling the strength
(stability) of the stripe order. We found that the onset temperature
, where the Nernst signal starts increasing, does not change
conspicuously in spite of Nd-doping. At low temperatures, on the other hand,
the absolute value of the Nernst signal is strongly suppressed in accordance
with the strength of the stripe order. These results imply that the fluctuation
of (charge) stripe order enhances the Nernst signal below at high
temperatures, and then the stripe order enhanced by Nd-doping suppresses the
superconducting fluctuation to reduce the Nernst signal at low temperatures. We
also observed an increase of the Nernst signal below the charge order
temperature which is observed in diffraction measurement.Comment: 3pages, 2figure
Universal Scaling Behavior of Anomalous Hall Effect and Anomalous Nernst Effect in Itinerant Ferromagnets
Anomalous Hall effect (AHE) and anomalous Nernst effect (ANE) in a variety of
ferromagnetic metals including pure metals, oxides, and chalcogenides, are
studied to obtain unified understandings of their origins. We show a universal
scaling behavior of anomalous Hall conductivity as a function of
longitudinal conductivity over five orders of magnitude, which is
well explained by a recent theory of the AHE taking into account both the
intrinsic and extrinsic contributions. ANE is closely related with AHE and
provides us with further information about the low-temperature electronic state
of itinerant ferromagnets. Temperature dependence of transverse Peltier
coefficient shows an almost similar behavior among various
ferromagnets, and this behavior is in good agreement quantitatively with that
expected from the Mott rule.Comment: 4pages, 4figures, 1tabl
EuSrMnO: a three-dimensional XY spin glass
The frequency, temperature, and dc-bias dependence of the ac-susceptibility
of a high quality single crystal of the EuSrMnO layered
manganite is investigated. EuSrMnO behaves like a XY spin
glass with a strong basal anisotropy. Dynamical and static scalings reveal a
three-dimensional phase transition near = 18 K, and yield critical
exponent values between those of Heisenberg- and Ising-like systems, albeit
slightly closer to the Ising case. Interestingly, as in the latter system, the
here observed rejuvenation effects are rather weak. The origin and nature of
the low temperature XY spin glass state is discussed.Comment: REVTeX 4 style; 5 pages, 4 figure
Growth, transport, and magnetic properties of Pr0.67Ca0.33MnO3 thin films
We have grown Pr0.67Ca0.33MnO3 thin films on LaAlO3 using pulsed laser deposition. Below 50 K, a field induced insulator-metal transition results in changes in resistivity of at least 6 orders of magnitude. The field induced conducting state is metastable at low temperature. The temperature dependence of the resistivity exhibits considerable hysteresis in a field of 40 kOe but becomes reversible in a field of 80 kOe
Anomalous Hall Effect and Magnetic Monopoles in Momentum-Space
Efforts to find the magnetic monopole in real space have been made in cosmic
rays and in accelerators, but up to now there is no firm evidence for its
existence due to the very heavy mass GeV. However, we show that
the magnetic monopole can appear in the crystal-momentum space of solids in the
accessible low energy region (eV) in the context of the anomalous
Hall effect. We report experimental results together with first-principles
calculations on the ferromagnetic crystal SrRuO that provide evidence for
the magnetic monopole in the crystal-momentum space.Comment: 4 figures, the supporting-online-materails are include
MD simulation of the Tat/Cyclin T1/CDK9 complex revealing the hidden catalytic cavity within the CDK9 molecule upon Tat binding
In this study, we applied molecular dynamics (MD) simulation to analyze the dynamic behavior of the Tat/CycT1/CDK9 tri-molecular complex and revealed the structural changes of P-TEFb upon Tat binding. We found that Tat could deliberately change the local flexibility of CycT1. Although the structural coordinates of the H1 and H2 helices did not substantially change, H1ʹ, H2ʹ, and H3ʹ exhibited significant changes en masse. Consequently, the CycT1 residues involved in Tat binding, namely Tat-recognition residues (TRRs), lost their flexibility with the addition of Tat to P-TEFb. In addition, we clarified the structural variation of CDK9 in complex with CycT1 in the presence or absence of Tat. Interestingly, Tat addition significantly reduced the structural variability of the T-loop, thus consolidating the structural integrity of P-TEFb. Finally, we deciphered the formation of the hidden catalytic cavity of CDK9 upon Tat binding. MD simulation revealed that the PITALRE signature sequence of CDK9 flips the inactive kinase cavity of CDK9 into the active form by connecting with Thr186, which is crucial for its activity, thus presumably recruiting the substrate peptide such as the C-terminal domain of RNA pol II. These findings provide vital information for the development of effective novel anti-HIV drugs with CDK9 catalytic activity as the target
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