SPONTANEOUS CURRENTS IN MESOSCOPIC RINGS

1992 ◽  
Vol 06 (24) ◽  
pp. 1481-1499 ◽  
Author(s):  
D. WOHLLEBEN ◽  
P. FRECHE ◽  
M. ESSER ◽  
E. ZIPPER ◽  
M. SZOPA
Keyword(s):  
Phase Transition ◽  
Critical Temperature ◽  
Elastic Scattering ◽  
Fermi Surface ◽  
Fermi Level ◽  
Magnetic Interaction ◽  
Quantum Size ◽  
A Current

In a system of mesoscopic rings the influence of orbital magnetic interaction between the electrons is investigated. At a critical temperature Tc the system undergoes a phase transition into a current carrying state. Tc depends strongly on geometry of the system and/or its Fermi-surface, and on the quantum size gap at the Fermi level. Elastic scattering reduces Tc and eventually suppresses the transition.

The sensitive tunability of superconducting critical temperature in high-buckled plumbene by shifting Fermi level

2021 ◽  
Vol 130 ◽  
pp. 114688
Author(s):  
Binyuan Zhang ◽  
Fei Guo ◽  
Mingfeng Zhu ◽  
Lanting Feng ◽  
Yisong Zheng
Keyword(s):  
Critical Temperature ◽  
Fermi Level

scholarly journals Cooper Pair-Like Systems at High Temperature and their Role on Fluctuations Near the Critical Temperature

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3216-3219 ◽  
Author(s):  
M. Ausloos ◽  
S. Dorbolo
Keyword(s):  
Phase Transition ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Critical Temperature ◽  
Oxygen Diffusion ◽  
Cooper Pair ◽  
Anomalous Behavior ◽  
Anomalous Effect ◽  
Linear Temperature ◽  
Ybco Sample

A logarithmic behavior is hidden in the linear temperature regime of the electrical resistivity R(T) of some YBCO sample below 2T c where "pairs" break apart, fluctuations occur and "a gap is opening". An anomalous effect also occurs near 200 K in the normal state Hall coefficient. In a simulation of oxygen diffusion in planar 123 YBCO, an anomalous behavior is found in the oxygen-vacancy motion near such a temperature. We claim that the behavior of the specific heat above and near the critical temperature should be reexamined in order to show the influence and implications of fluctuations and dimensionality on the nature of the phase transition and on the true onset temperature.

scholarly journals Strong correlation between electronic bonding network and critical temperature in hydrogen-based superconductors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Francesco Belli ◽  
Trinidad Novoa ◽  
J. Contreras-García ◽  
Ion Errea
Keyword(s):  
Critical Temperature ◽  
Physical Properties ◽  
Fermi Level ◽  
Electronic Properties ◽  
Density Of States ◽  
Strong Correlation ◽  
Critical Temperatures ◽  
Structural And Electronic Properties ◽  
Superconducting Compounds ◽  
Better Than

AbstractBy analyzing structural and electronic properties of more than a hundred predicted hydrogen-based superconductors, we determine that the capacity of creating an electronic bonding network between localized units is key to enhance the critical temperature in hydrogen-based superconductors. We define a magnitude named as the networking value, which correlates with the predicted critical temperature better than any other descriptor analyzed thus far. By classifying the studied compounds according to their bonding nature, we observe that such correlation is bonding-type independent, showing a broad scope and generality. Furthermore, combining the networking value with the hydrogen fraction in the system and the hydrogen contribution to the density of states at the Fermi level, we can predict the critical temperature of hydrogen-based compounds with an accuracy of about 60 K. Such correlation is useful to screen new superconducting compounds and offers a deeper understating of the chemical and physical properties of hydrogen-based superconductors, while setting clear paths for chemically engineering their critical temperatures.

Nematic-Smectic a Phase-Transition Under Shear Flow

1989 ◽  
Vol 177 ◽  
Author(s):  
R. F. Bruinsma ◽  
C. R. Safinya
Keyword(s):  
Phase Transition ◽  
Critical Temperature ◽  
Shear Flow ◽  
Structure Factor ◽  
Deborah Number ◽  
Flow Properties ◽  
Newtonian Flow ◽  
One Dimensional ◽  
Smectic A ◽  
Smectic A Phase

ABSTRACTWe discuss the effect of shear flow on the nematic to smectic A phase transition. The non-Newtonian flow properties (shear thinning and normal stress) ire correlated with the distortions of the structure-factor S(q). As a function of the Deborah number, we find first a deformation of S(q) and, beyond a critical Deborah number, highly distorted, one-dimensional fluctuations. The suppression of fluctuations by shear flow raises the critical temperature.

scholarly journals Holographic Lifshitz superconductors with Weyl correction

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Jun-Wang Lu ◽  
Ya-Bo Wu ◽  
Bao-Ping Dong ◽  
Yu Zhang
Keyword(s):  
Phase Transition ◽  
Black Hole ◽  
Critical Temperature ◽  
Numerical Method ◽  
Analytical Methods ◽  
Competitive Effects ◽  
Lifshitz Black Hole ◽  
The Difference ◽  
Lower Temperature ◽  
Numerical And Analytical Methods

AbstractAt the probe approximation, we construct a holographic p-wave conductor/superconductor model in the five-dimensional Lifshitz black hole with the Weyl correction via both numerical and analytical methods, and study the effects of the Lifshitz parameter z as well as the Weyl parameter $$\gamma $$ γ on the superconductor model. As we take into account one of the two corrections separately, the increasing z ($$\gamma $$ γ ) inhibits(enhances) the superconductor phase transition. When the two corrections are considered comprehensively, they display the obviously competitive effects on both the critical temperature and the vector condensate. In particular, the promoting effects of the Weyl parameter $$\gamma $$ γ on the critical temperature are obviously suppressed by the increasing Lifshitz parameter. Meanwhile, in the case of $$z<2.35$$ z < 2.35 ($$z>2.35$$ z > 2.35 ), the condensate at lower temperature decreases(increases) with the increasing Weyl parameter $$\gamma $$ γ . What is more, the difference among the condensate with the fixed Weyl parameter($$\gamma =-\frac{6}{100},0,\frac{4}{100}$$ γ = - 6 100 , 0 , 4 100 ) decreases(increases) with the increasing Lifshitz parameter z in the region $$z<2.35$$ z < 2.35 ($$z>2.35$$ z > 2.35 ). Furthermore, the increasing z obviously suppresses the real part of conductivity for all value of the Weyl parameter $$\gamma $$ γ . In addition, the analytical results agree well with the ones from the numerical method.

scholarly journals Holographic s-wave superconductors with Horndeski correction

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Jun-Wang Lu ◽  
Ya-Bo Wu ◽  
Li-Gong Mi ◽  
Hao Liao ◽  
Bao-Ping Dong
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Critical Temperature ◽  
Chemical Potential ◽  
Low Frequency ◽  
S Wave ◽  
Quasiparticle Excitation ◽  
Numerical Result ◽  
Ads Black Holes ◽  
Numerical And Analytical Methods

Abstract Via both numerical and analytical methods, we build the holographic s-wave insulator/superconductor model in the five-dimensional AdS soliton with the Horndeski correction in the probe limit and study the effects of Horndeski parameter k on the superconductor model. For the fixed mass squared of the scalar field ($$m^2$$m2), the critical chemical potential $$\mu _c$$μc increases with the larger Horndeski parameter k, which means that the increasing Horndeski correction hinders the superconductor phase transition. Meanwhile, above the critical chemical potential, the obvious pole arises in the low frequency of the imaginal part of conductivity, which signs the appearance of superconducting state. What is more, the energy of quasiparticle excitation decreases with the larger Horndeski correction. Furthermore, the critical exponent of the condensate (charge density) is $$\frac{1}{2}$$12 (1), which is independent of the Horndeski correction. In addition, the analytical results agree well with the numerical results. Subsequently, the conductor/superconductor model with Horndeski correction is analytically realized in the four- and five-dimensional AdS black holes. It is observed that the increasing Horndeski correction decreases the critical temperature and thus hinders the superconductor phase transition, which agrees with the numerical result in the previous works.

scholarly journals Manipulating the critical temperature for the superfluid phase transition in trapped atomic Fermi gases

2002 ◽  
Vol 65 (6) ◽  
Author(s):  
C. P. Search ◽  
H. Pu ◽  
W. Zhang ◽  
B. P. Anderson ◽  
P. Meystre
Keyword(s):  
Phase Transition ◽  
Critical Temperature ◽  
Fermi Gases ◽  
Superfluid Phase

SPECTRUM OF SCREENING MASSES FOR SU(2) GAUGE THEORY: UNIVERSALITY CLASS

2010 ◽  
Vol 19 (08n10) ◽  
pp. 1725-1729
Author(s):  
R. S. COSTA ◽  
S. B. DUARTE ◽  
M. CHIAPPARINI ◽  
T. MENDES
Keyword(s):  
Phase Transition ◽  
Monte Carlo ◽  
Gauge Theory ◽  
Critical Temperature ◽  
Variational Method ◽  
Excited States ◽  
Universality Class ◽  
Yang Mills ◽  
Exponential Method ◽  
Deconfinement Phase Transition

In this work we study the spectrum of the lowest screening masses for Yang–Mills theories on the lattice. We used the SU(2) gauge group in (3 + 1) dmensions. We adopted the multiple exponential method and the so-called "variational" method, in order to detect possible excited states. The calculations were done near the critical temperature of the confinement-deconfinement phase transition. We obtained values for the ratios of the screening masses consistent with predictions from universality arguments. A Monte Carlo evolution of the screening masses in the gauge theory confirms the validity of the predictions.

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