AN ALTERNATIVE APPROACH TO MULTI-GAP SUPERCONDUCTIVITY

2013 ◽  
Vol 27 (29) ◽  
pp. 1347008 ◽  
Author(s):  
G. P. MALIK ◽  
M. DE LLANO
Keyword(s):  
Critical Temperature ◽  
Interaction Parameters ◽  
Zero Temperature ◽  
Superconducting Properties ◽  
Temperature Dependent ◽  
Alternative Approach ◽  
Derived Set ◽  
Quantitative Explanation

We draw attention to a feature suggested by a widely-cited paper by Suhl, Matthias, and Walker in the context of multi-gap superconductivity that seems to have escaped serious attention: interaction parameters in a superconductor characterized by two zero-temperature gaps but a single critical temperature must be temperature-dependent. Guided by this cue, we have presented a plausible scenario for a quantitative explanation of the superconducting properties of MgB 2 via an alternative approach — the approach provided by the recently derived set of generalized-BCS equations. Attention is drawn to earlier work in diverse fields where a similar T-dependent approach has been fruitful.

AN IMPROVED ONE-LOOP ANALYSIS OF THE λϕ4 THEORY AT FINITE TEMPERATURE

1987 ◽  
Vol 02 (03) ◽  
pp. 713-728 ◽  
Author(s):  
SWEE-PING CHIA
Keyword(s):  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Zero Temperature ◽  
Coupling Constant ◽  
Loop Analysis ◽  
Temperature Dependent ◽  
Effective Coupling ◽  
Loop Approximation ◽  
The One ◽  
Dependent Mass

The λϕ4 theory with tachyonic mass is analyzed at T ≠ 0 using an improved one-loop approximation in which each of the bare propagators in the one-loop diagram is replaced by a dressed propagator to take into account the higher loop effects. The dressed propagator is characterized by a temperature-dependent mass which is determined by a self-consistent relation. Renomalization is found to be necessarily temperature-dependent. Real effective potential is obtained, giving rise to real effective mass and real coupling constant. For T < Tc, this is achieved by first shifting the ϕ field by its zero-temperature vacuum expectation value. The effective coupling constant is found to exhibit the striking behavior that it approaches a constant nonzero value as T → ∞.

An Alternative Approach to Analyzing the Interstitial Decay from the End of Range Damage During Millisecond Annealing

2008 ◽  
Vol 1070 ◽  
Author(s):  
Renata Camillo-Castillo ◽  
Mark E Law ◽  
Kevin S Jones
Keyword(s):  
Annealing Time ◽  
Dwell Time ◽  
Extended Defects ◽  
Temperature Dependent ◽  
Temperature Regimes ◽  
Alternative Approach ◽  
Small Times ◽  
Conventional Annealing ◽  
Kinetics Of ◽  
Anneal Temperature

ABSTRACTFlash-assist Rapid Thermal Processing (RTP) presents an opportunity to investigate annealing time and temperature regimes which were previously not accessible with conventional annealing techniques such as Rapid Thermal Annealing. This provides a unique opportunity to explore the early stages of the End of Range (EOR) damage evolution and also to examine how the damage evolves during the high temperature portion of the temperature profile. However, the nature of the Flash-assist RTP makes it is extremely difficult to reasonably compare it to alternative annealing techniques, largely because the annealing time at a given temperature is dictated by the FWHM of the radiation pulse. The FWHM for current flash tools vary between 0.85 and 1.38 milliseconds, which is three orders of magnitude smaller to that required for a RTA to achieve similar temperatures. Traditionally, the kinetics of the extended defects has been studied by time dependent studies utilizing isothermal anneals; in which specific defect structures could be isolated. The characteristics of Flash-assist RTP do not allow for such investigations in which the EOR defect evolution could be closely tracked with time. Since the annealing time at the target temperature for the Flash-assist RTP is essentially fixed to very small times on the order of milliseconds, isochronal anneals are a logical experimental approach to temperature dependent studies. This fact presents a challenge in the data analysis and comparison. Another feature of Flash-assist RTP which makes the analysis complex is the ramp time relative to the dwell time spent at the peak fRTP temperature. As the flash anneal temperature is increased the total ramp time can exceed the dwell time at the peak temperature, which may play a significantly larger role in dictating the final material properties. The inherent characteristics of Flash-assist RTP have consequently required the development of another approach to analyzing the attainable experimental data, such that a meaningful comparison could be made to past studies. The adopted analysis entails the selection of a reference anneal, from which the decay in the trapped interstitial density can be tracked with the flash anneal temperature, allowing for the kinetics of the interstitial decay to be extracted.

scholarly journals Thermal Tolerance of Fruit-Feeding Butterflies (Lepidoptera: Nymphalidae) in Contrasting Mountaintop Environments

Insects ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 278 ◽  
Author(s):  
Vanessa Diniz e Silva ◽  
Marina Vale Beirão ◽  
Danon Clemes Cardoso
Keyword(s):  
Climate Change ◽  
Critical Temperature ◽  
Thermal Tolerance ◽  
Global Climate ◽  
Campo Rupestre ◽  
Temperature Dependent ◽  
Physiological Constraints ◽  
Resistant Species ◽  
Complicated Task ◽  
Forest Islands

Ectothermic organisms, such as insects, are highly temperature dependent and are good models for studies that predict organisms’ responses to global climate change. Predicting how climate change may affect species distributions is a complicated task. However, it is possible to estimate species’ physiological constraints through maximum critical temperature, which may indicate if the species can tolerate new climates. Butterflies are useful organisms for studies of thermal tolerance. We tested if species have different thermal tolerances and if different habitats influence the thermal tolerance of the butterflies present in Brazil’s campo rupestre (open areas) and forest islands (shaded areas). A total of 394 fruit-feeding butterflies, comprising 45 species, were tested. The results separated the species into two statistically different groups: the resistant species with maximum critical temperature of 53.8 ± 7.4 °C, and the non-resistant species with maximum critical temperature of 48.2 ± 7.4 °C. The species of butterflies displayed differences in maximum critical temperature between the campo rupestre and forest islands that can be related to the two distinct habitats, but this did not correlate phylogenetically. Species from the forest islands were also divided into two groups, “resistant” and “non-resistant”, probably due to the heterogeneity of the habitat; the forest islands have a canopy, and in the understory, there are shaded and sunny areas. Species from forest islands, especially species that displayed lower thermal tolerance, may be more susceptible to global warming.

THERMOFIELD ANALYSIS OF MAGNON SQUEEZING STATE IN THE FERROMAGNET

2008 ◽  
Vol 22 (20) ◽  
pp. 1931-1939
Author(s):  
QINFENG XU ◽  
ZE CHENG ◽  
YUNXIA PING
Keyword(s):  
Thermal Field ◽  
Zero Point ◽  
Vacuum State ◽  
Field Approximation ◽  
Spin Component ◽  
Zero Temperature ◽  
Temperature Dependent ◽  
Consistent Field ◽  
Self Consistent Field ◽  
Lower Temperature

In this paper, we introduce the self-consistent field approximation to treat with the nonlinear interaction among spin waves. Then temperature-dependent Bogoliubov transformation is introduced to generate a new representation which engenders the transition from the zero temperature to the finite temperature. At last, temperature-dependent quantum fluctuation properties of magnons are discussed in the thermal field. At lower temperature, we find that the fluctuation of spin-component at some given time regions can be below the zero-point fluctuation level of the vacuum state and exhibit a periodical squeezing behavior. In particular, these squeezed effects vanish with the increasing of temperature. These squeezing effects differ from the previous studies.

Logarithmic Factors, Critical Temperature, and Zero Temperature Flipping in the 4D Kinetic Ising Model

1997 ◽  
Vol 08 (02) ◽  
pp. 263-267 ◽  
Author(s):  
Dietrich Stauffer ◽  
Joan Adler
Keyword(s):  
Critical Temperature ◽  
Ising Model ◽  
Nearest Neighbor ◽  
Kinetic Monte Carlo ◽  
Series Expansions ◽  
Fourth Moment ◽  
Zero Temperature ◽  
Kinetic Ising Model ◽  
Kinetic Monte Carlo Simulations ◽  
Error Bars

We determine the critical temperature in the four-dimensional nearest-neighbor Ising model as J/kB Tc=0.149694±0.000002 from kinetic Monte Carlo simulations of up to 5764 spins. Here we assume the critical magnetization to decay with time as (t/ log t)-1/2. However, possible logarithmic additions to this leading scaling behavior could change the estimate beyond these error bars. A reanalyzis of old series expansions for the susceptibility and fourth moment gives 0.149696±0.000004.

EFFECTIVE THEORY OF BOSONIC SUPERFLUIDS

1994 ◽  
Vol 08 (15) ◽  
pp. 2021-2039 ◽  
Author(s):  
ADRIAAN M.J. SCHAKEL
Keyword(s):  
Critical Temperature ◽  
Weak Coupling ◽  
Particle Number ◽  
Landau Theory ◽  
Effective Theory ◽  
Bcs Theory ◽  
Goldstone Mode ◽  
Zero Temperature ◽  
Temperature Expansion ◽  
High Temperature Expansion

We discuss the effective theory of a bosonic superfluid whose microscopic behavior is described by a nonrelativistic, weak-coupling Φ4 theory in the phase with broken particle number symmetry, both at zero temperature and in the vicinity of the phase transition. In the zero-temperature regime, the theory is governed by the gapless Goldstone mode resulting from the broken .symmetry. Although this mode is gapless, the effective theory turns out to be Gallilei invariant. The regime just below the critical temperature is approached in a high-temperature expansion which is shown to be consistent with the weak-coupling assumption of the theory. We calculate the critical temperature, the co-efficients of the Landau theory, and the finite-temperature sound velocity. A comparison with BCS theory is given.

Temperature Dependence of Amorphization above 10K in the CuTi Intermetallic Compound Under Electron Irradiation

1986 ◽  
Vol 74 ◽  
Author(s):  
J. Koike ◽  
D. E. Oluzzi ◽  
M. Meshii ◽  
P. R. Okamoto
Keyword(s):  
Critical Temperature ◽  
Intermetallic Compound ◽  
Cluster Formation ◽  
Irradiation Temperature ◽  
Crystalline Compound ◽  
Temperature Dependent ◽  
Defect Clusters ◽  
Critical Dose ◽  
Increasing Temperature ◽  
Critical Temperature Tc

AbstractThe critical dose required to amorphize the crystalline compound CuTi during irradiation with 1 MeV electrons has been investigated from 10 to 288 K. The results show that above a critical temperature (Tc) of about 185 K, CuTi remains crystalline and only defect clusters are formed. Below Tc, amorphization occurs with no observable cluster formation. The critical dose for amorphization was found to be temperature dependent below Tc: as the irradiation temperature increases, a higher dose is required to induce amorphization. This observation supports the concept that Tc corresponds to the vacancy migration temperature. Below Tc, interstitial migration may contribute to the observed reduction in the amorphization rate with increasing temperature.

Connectivity and flux pinning improvements in Ag-clad BSCCO-2223 tapes produced by changes in the cooling rate

1997 ◽  
Vol 12 (11) ◽  
pp. 2997-3008 ◽  
Author(s):  
J. A. Parrell ◽  
D. C. Larbalestier ◽  
G. N. Riley ◽  
Q. Li ◽  
W. L. Carter ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Critical Temperature ◽  
Cooling Rate ◽  
Flux Pinning ◽  
Irreversibility Field ◽  
Superconducting Properties ◽  
Temperature Transition ◽  
Slow Cooling ◽  
Reaction Heat ◽  
Final Reaction

The rate at which Ag-clad (Bi, Pb)2Sr2Ca2Cu3Ox tapes are cooled from their final reaction heat treatment influences both the intergranular connectivity and intragranular flux pinning strength of the polycrystalline filaments. As the cooling rate from 825 °C to 730 °C in 7.5% O2 was decreased over a range of 5 °C/min to 0.005 °C/min, Jc (77 K, 0 T) increased from ∼8 to ∼24 kA/cm2, and the irreversibility field increased from, ∼120 to, ∼200 mT. The Jc (4.2 K, 0 T) increased in a similar fashion. Cooling slowly also sharpened the critical temperature transition and increased the critical onset temperature from 107 K to 109 K. These improvements in the superconducting properties occurred despite partial decomposition of the (Bi, Pb)2Sr2Ca2Cu3Ox phase into non-superconducting impurity phases during the slow cooling. A microstructural basis for these multiple effects is described.

COLOR CONFINEMENT AND FINITE TEMPERATURE QCD PHASE TRANSITION

2004 ◽  
Vol 19 (02) ◽  
pp. 271-285 ◽  
Author(s):  
H. C. PANDEY ◽  
H. C. CHANDOLA ◽  
H. DEHNEN
Keyword(s):  
Phase Transition ◽  
Critical Temperature ◽  
Effective Potential ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Zero Temperature ◽  
Expectation Value ◽  
Qcd Phase Transition ◽  
Qcd Vacuum ◽  
Color Confinement

We study an effective theory of QCD in which the fundamental variables are dual magnetic potentials coupled to the monopole field. Dual dynamics are then used to explain the properties of QCD vacuum at zero temperature as well as at finite temperatures. At zero temperature, the color confinement is realized through the dynamical breaking of magnetic symmetry, which leads to the magnetic condensation of QCD vacuum. The flux tube structure of SU(2) QCD vacuum is investigated by solving the field equations in the low energy regimes of the theory, which guarantees dual superconducting nature of the QCD vacuum. The QCD phase transition at finite temperature is studied by the functional diagrammatic evaluation of the effective potential on the one-loop level. We then obtained analytical expressions for the vacuum expectation value of the condensed monopoles as well as the masses of glueballs from the temperature dependent effective potential. These nonperturbative parameters are also evaluated numerically and used to determine the critical temperature of the QCD phase transition. Finally, it is shown that near the critical temperature (Tc≃0.195 GeV ), continuous reduction of vacuum expectation value (VEV) of the condensed monopoles caused the disappearance of vector and scalar glueball masses, which brings a second order phase transition in pure SU(2) gauge QCD.

scholarly journals CRITICAL TEMPERATURE AND AMPLITUDE RATIOS FROM A FINITE TEMPERATURE RENORMALIZATION GROUP

1995 ◽  
Vol 10 (23) ◽  
pp. 3343-3358 ◽  
Author(s):  
M.A. VAN EIJCK ◽  
DENJOE O’CONNOR ◽  
C.R. STEPHENS
Keyword(s):  
Renormalization Group ◽  
Critical Temperature ◽  
Finite Temperature ◽  
Flow Parameter ◽  
Three Dimensional ◽  
Zero Temperature ◽  
Amplitude Ratios ◽  
Flow Equations ◽  
Infrared Divergences ◽  
Good Agreement

We study λφ4 theory using an environmentally friendly finite temperature renormalization group. We derive flow equations, using a fiducial temperature as flow parameter, develop them perturbatively in an expansion free from ultraviolet and infrared divergences, then integrate them numerically from zero to temperatures above the critical temperature. The critical temperature, at which the mass vanishes, is obtained by integrating the flow equations, and is determined as a function of the zero temperature mass and coupling. We calculate the field expectation value and the minimum of the effective potential as functions of temperature and derive some universal amplitude ratios which connect the broken and symmetric phases of the theory. The latter are found to be in good agreement with those of the three-dimensional Ising model obtained from high and low temperature series expansions.

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