140 research outputs found
Dependence of vortex phase transitions in mesoscopic BSCCO superconductor at tilted magnetic fields
A micron sized single crystal of the superconductor BSCCO was studied using
silicon mechanical micro-oscillators at various tilt angles of the dc magnetic
field with respect to the c axis of the sample. Different phases of the vortex
matter were detected by measuring changes in the value and sign of the
oscillator resonant frequency variation with temperature. We could explain the
change in the sign of this variation at high temperatures as the transition
from the 2D liquid of decoupled pancakes to a reversible 3D vortex lattice. The
data indicates that this transition only depends on the magnetic field
perpendicular to the superconducting layers while the dissipation involved in
this process depends on the component parallel to them.Comment: 4 pages, 4 figure
Latent-heat and non-linear vortex liquid at the vicinity of the first-order phase transition in layered high-Tc superconductors
In this work we revisit the vortex matter phase diagram in layered
superconductors solving still open questions by means of AC and DC local
magnetic measurements in the paradigmatic BiSrCaCuO
compound. We show that measuring with AC magnetic techniques is mandatory in
order to probe the bulk response of vortex matter, particularly at
high-temperatures where surface barriers for vortex entrance dominate. From the
-evolution of the enthalpy and latent-heat at the transition we
find that, contrary to previous reports, the nature of the dominant interlayer
coupling is electromagnetic in the whole temperature range. By studying the
dynamic properties of the phase located at , we reveal
the spanning in a considerable fraction of the phase diagram of a non-linear
vortex phase suggesting bulk pinning might play a role even in the liquid
vortex phase.Comment: arXiv admin note: substantial text overlap with arXiv:1212.456
Anisotropic response of the moving vortex lattice in superconducting MoGe amorphous films
We have performed magnetic susceptibility measurements in MoGe
amorphous thin films biased with an electrical current using anisotropic coils.
We tested the symmetry of the vortex response changing the relative orientation
between the bias current and the susceptibility coils. We found a region in the
DC current - temperature phase diagram where the dynamical vortex structures
behave anisotropically. In this region the shielding capability of the
superconducting currents measured by the susceptibility coils is less effective
along the direction of vortex motion compared to the transverse direction. This
anisotropic response is found in the same region where the peak effect in the
critical current is developed. On rising temperature the isotropic behavior is
recovered.Comment: 10 pages, 4 figure
Energy-Aware High Performance Computing
High performance computing centres consume substantial amounts of energy to power large-scale supercomputers and the necessary building and cooling infrastructure. Recently, considerable performance gains resulted predominantly from developments in multi-core, many-core and accelerator technology. Computing centres rapidly adopted this hardware to serve the increasing demand for computational power. However, further performance increases in large-scale computing systems are limited by the aggregate energy budget required to operate them. Power consumption has become a major cost factor for computing centres. Furthermore, energy consumption results in carbon dioxide emissions, a hazard for the environment and public health; and heat, which reduces the reliability and lifetime of hardware components. Energy efficiency is therefore crucial in high performance computing
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