Sharp resonant multiplet in femtosecond optical pair-breaking spectroscopy of optimally doped, underdoped, and Zn-dopedYBa2Cu3O7−δ: Transient insulating regions in the superconducting state

2002 ◽  
Vol 65 (18) ◽  
Author(s):  
Eric Li ◽  
R. P. Sharma ◽  
S. B. Ogale ◽  
Y. G. Zhao ◽  
T. Venkatesan ◽  
...  
Keyword(s):  
Superconducting State ◽  
Pair Breaking

NOVEL TRANSPORT BEHAVIOR FOUND IN THE DISSIPATIVE REGIME OF SUPERCONDUCTORS

1995 ◽  
Vol 09 (07) ◽  
pp. 399-426 ◽  
Author(s):  
MILIND N. KUNCHUR
Keyword(s):  
Kinetic Energy ◽  
Superconducting State ◽  
Interlayer Coupling ◽  
Pair Breaking ◽  
Condensation Energy ◽  
Flux Flow ◽  
Transport Behavior ◽  
Pair Condensation ◽  
Physical Phenomena ◽  
First Time

As the transport current density J in a superconductor is increased beyond its critical value J c , dissipation sets in resulting in a finite resistivity. The superconducting state itself, however, persists up to the pair-breaking value J d , where the kinetic energy associated with the current overcomes the condensation energy. Within this dissipative regime between J c and J d , the transport behavior displays a series of interesting physical phenomena (free flux flow, pair-breaking effect, etc.) as the Lorentz force and kinetic energy associated with the current sequentially overcome various intrinsic (e.g., pair-condensation and interlayer-coupling) and extrinsic (e.g., flux pinning) interactions relevant to the superconducting state. This review discusses these phenomena in the context of recent experiments where the existence of these effects was demonstrated in high-T c superconductors for the first time. Also described are the general principles of the pulsed-current technique used to extend transport measurements to the required high current densities and power-dissipation levels.

Superconducting State under the Influence of External Dynamic Pair Breaking

1972 ◽  
Vol 28 (24) ◽  
pp. 1559-1561 ◽  
Author(s):  
C. S. Owen ◽  
D. J. Scalapino
Keyword(s):  
Superconducting State ◽  
Pair Breaking

scholarly journals Pair-Breaking and Superconducting State Recovery Dynamics inMgB2

2003 ◽  
Vol 91 (26) ◽  
Author(s):  
J. Demsar ◽  
R. D. Averitt ◽  
A. J. Taylor ◽  
V. V. Kabanov ◽  
W. N. Kang ◽  
...  
Keyword(s):  
Superconducting State ◽  
Pair Breaking ◽  
State Recovery ◽  
Recovery Dynamics

scholarly journals Inhomogeneous Superconductivity and the ‘Pseudogap’ State of Novel Superconductors

2021 ◽  
pp. 281-308
Author(s):  
Vladimir Z. Kresin ◽  
Sergei G. Ovchinnikov ◽  
Stuart A. Wolf
Keyword(s):  
Critical Temperature ◽  
Isotope Effect ◽  
Superconducting State ◽  
Energy Gap ◽  
Metallic Matrix ◽  
Superconducting Phase ◽  
Pair Breaking ◽  
Statistical Nature ◽  
Breaking Effect ◽  
Granular Superconductors

This chapter discusses the high-Tc oxides, which display many unusual properties above Tc, especially for the underdoped compounds. One can observe some features typical for the superconducting state, such as the energy gap, anomalous diamagnetism, and the isotope effect; they coexist with finite resistance. These features are caused by an intrinsic inhomogeneity of the compound. Various energy scales (Tc, Tc*, T*) can be introduced. The system contains a set of superconducting ‘islands’ embedded in a normal metallic matrix. The inhomogeneity is caused by the statistical nature of doping and the pair-breaking effect. The formation of a macroscopic superconducting phase (at T = Tc) corresponds to the transition, which is of a percolative nature. The resistive and Meissner transitions are split. The granular superconductors are inhomogeneous and their properties are similar to those of doped systems. The ordered doping should lead to an increase in the value of the critical temperature.

Observation by HVEM of the martensite transformation and the superconducting transition in Nb3Sn

1988 ◽  
Vol 46 ◽  
pp. 788-789
Author(s):  
M. A. Kirk ◽  
M. C. Baker ◽  
B. J. Kestel ◽  
H. W. Weber
Keyword(s):  
Thin Films ◽  
Low Temperature ◽  
Superconducting State ◽  
Martensite Transformation ◽  
Sputter Deposition ◽  
Diffusion Reaction ◽  
Solute Diffusion ◽  
Superconducting Transition ◽  
Twin Boundaries ◽  
Martensite Structure

It is well known that a number of compound superconductors with the A15 structure undergo a martensite transformation when cooled to the superconducting state. Nb3Sn is one of those compounds that transforms, at least partially, from a cubic to tetragonal structure near 43 K. To our knowledge this transformation in Nb3Sn has not been studied by TEM. In fact, the only low temperature TEM study of an A15 material, V3Si, was performed by Goringe and Valdre over 20 years ago. They found the martensite structure in some foil areas at temperatures between 11 and 29 K, accompanied by faults that consisted of coherent twin boundaries on {110} planes. In pursuing our studies of irradiation defects in superconductors, we are the first to observe by TEM a similar martensite structure in Nb3Sn.Samples of Nb3Sn suitable for TEM studies have been produced by both a liquid solute diffusion reaction and by sputter deposition of thin films.

Systems with Condensates and Pairing

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Critical Parameters ◽  
Einstein Condensation ◽  
Cooper Pairs ◽  
Pair Breaking ◽  
Systematic Theory ◽  
Bose Einstein Condensation ◽  
T Matrix ◽  
The Stability ◽  
Bose Einstein

The Bose–Einstein condensation and appearance of superfluidity and superconductivity are introduced from basic phenomena. A systematic theory based on the asymmetric expansion of chapter 11 is shown to correct the T-matrix from unphysical multiple-scattering events. The resulting generalised Soven scheme provides the Beliaev equations for Boson’s and the Nambu–Gorkov equations for fermions without the usage of anomalous and non-conserving propagators. This systematic theory allows calculating the fluctuations above and below the critical parameters. Gap equations and Bogoliubov–DeGennes equations are derived from this theory. Interacting Bose systems with finite temperatures are discussed with successively better approximations ranging from Bogoliubov and Popov up to corrected T-matrices. For superconductivity, the asymmetric theory leading to the corrected T-matrix allows for establishing the stability of the condensate and decides correctly about the pair-breaking mechanisms in contrast to conventional approaches. The relation between the correlated density from nonlocal kinetic theory and the density of Cooper pairs is shown.

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