772 research outputs found
Calorimetric Measurements of Magnetic-Field-Induced Inhomogeneous Superconductivity Above The Paramagnetic Limit
We report the first magneto-caloric and calorimetric observations of a
magnetic-field-induced phase transition within a superconducting state to the
long-sought exotic "FFLO" superconducting state first predicted over 50 years
ago. Through the combination of bulk thermodynamic calorimetric and
magnetocaloric measurements in the organic superconductor -
(BEDT-TTF)Cu(NCS), as a function of temperature, magnetic field
strength, and magnetic field orientation, we establish for the first time that
this field-induced first-order phase transition at the paramagnetic limit
for traditional superconductivity is to a higher entropy superconducting phase
uniquely characteristic of the FFLO state. We also establish that this
high-field superconducting state displays the bulk paramagnetic ordering of
spin domains required of the FFLO state. These results rule out the alternate
possibility of spin-density wave (SDW) ordering in the high field
superconducting phase. The phase diagram determined from our measurements ---
including the observation of a phase transition into the FFLO phase at
--- is in good agreement with recent NMR results and our own earlier
tunnel-diode magnetic penetration depth experiments, but is in disagreement
with the only previous calorimetric report.Comment: 5 pages, 5 figure
The Land Cadastre in Italy and some fiscal implications: a case study
The Land Cadastre, as an inventory of all relevant real estate in a territory, and most importantly, as a national tax system is, or at least should be, the protago-nist of fiscal, social and civil implications affecting the Italian context. According to unitary farmland incomes, the last revision dates back to 1978-1979, a period that no longer reflects the country’s current socioeconomic situation and does not consider the changes the land market has undergone over the years. Through the analysis of 183 purchases and sales of agricultural land in two districts in western Sicily, this research aims at verifying the adequacy or inadequacy of the current cadastral tariffs. Based on the prices surveyed and the cadastral farmland incomes, some indicators were constructed showing, on the one hand the absence of a strict correspondence between these two values and on the other hand the actual presence of fiscal ine-quality for all the crop qualities examined; and, consequently, the need for revising cadastral tariffs or for reforming tax system of Italian Cadastre by replacing tariffs with market values
JIST: just-in-time scheduling translation for parallel processors
The application fields of bytecode virtual machines and VLIW processors overlap in the area of embedded and mobile systems, where the two technologies offer different benefits, namely high code portability, low power consumption and reduced hardware cost. Dynamic compilation makes it possible to bridge the gap between the two technologies, but special attention must be paid to software instruction scheduling, a must for the VLIW architectures. We have implemented JIST, a Virtual Machine and JIT compiler for Java Bytecode targeted to a VLIW processor. We show the impact of various optimizations on the performance of code compiled with JIST through the experimental study on a set of benchmark programs. We report significant speedups, and increments in the number of instructions issued per cycle up to 50% with respect to the non-scheduling version of the JITcompiler. Further optimizations are discussed
A bulk 2D Pauli Limited Superconductor
We present a nearly perfect Pauli-limited critical field phase diagram for
the anisotropic organic superconductor \-(ET)NH(SCN) when
the applied magnetic field is oriented parallel to the conducting layers. The
critical fields ({H_{c_2}) were found by use of penetration depth
measurements. Because {H_{c_2} is Pauli-limited, the size of the
superconducting energy gap can be calculated. The role of spin-orbit scattering
and many-body effects play a role in explaining our measurements.Comment: 4 pages, 5 figures. V5, corrections were made to the text, present
data was include
Upper critical field study in the organic superconductor -(ET)SFCHCFSO : Possibility of Fulde-Ferrell-Larkin-Ovchinnikov state
We report upper critical field measurements in the metal-free-all-organic
superconductor -(ET)SFCHCFSO obtained
from measuring the in-plane penetration depth using the tunnel diode oscillator
technique. For magnetic field applied parallel to the conducting planes the low
temperature upper critical fields are found to exceed the Pauli limiting field
calculated by using a semi-empirical method. Furthermore, we found a signature
that could be the phase transition between the superconducting vortex state and
the Fulde-Ferrell-Larkin-Ovchinnikov state in the form of a kink just below the
upper critical field and only at temperatures below 1.23 K.Comment: 4 pages, 6 figure
An Experimental and Semi-Empirical Method to Determine the Pauli-Limiting Field in Quasi 2D Superconductors as applied to -(BEDT-TTF)Cu(NCS): Strong Evidence of a FFLO State
We present upper critical field data for -(BEDT-TTF)Cu(NCS)
with the magnetic field close to parallel and parallel to the conducting
layers. We show that we can eliminate the effect of vortex dynamics in these
layered materials if the layers are oriented within 0.3 degrees of parallel to
the applied magnetic field. Eliminating vortex effects leaves one remaining
feature in the data that corresponds to the Pauli paramagnetic limit ().
We propose a semi-empirical method to calculate the in quasi 2D
superconductors. This method takes into account the energy gap of each of the
quasi 2D superconductors, which is calculated from specific heat data, and the
influence of many body effects. The calculated Pauli paramagnetic limits are
then compared to critical field data for the title compound and other organic
conductors. Many of the examined quasi 2D superconductors, including the above
organic superconductors and CeCoIn, exhibit upper critical fields that
exceed their calculated suggesting unconventional superconductivity. We
show that the high field low temperature state in
-(BEDT-TTF)Cu(NCS) is consistent with the Fulde Ferrell Larkin
Ovchinnikov state.Comment: 8 pages, 9 figures, 10 years of dat
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