scholarly journals s-Wave Symmetry Along the c-Axis and s+d In-plane Superconductivity in Bulk YBa2Cu4O8

2007 ◽  
Vol 21 (2) ◽  
pp. 81-85 ◽  
Author(s):  
R. Khasanov ◽  
A. Shengelaya ◽  
J. Karpinski ◽  
A. Bussmann-Holder ◽  
H. Keller ◽  
...  
Keyword(s):  
S Wave ◽  
Wave Symmetry

Superconducting Gap in s±-Wave Iron-Based Superconductors

SPIN ◽  
2018 ◽  
Vol 08 (02) ◽  
pp. 1850006
Author(s):  
B. Pradhan ◽  
S. K. Goi ◽  
R. N. Mishra
Keyword(s):  
Nearest Neighbor ◽  
Energy Gap ◽  
S Wave ◽  
Iron Based Superconductors ◽  
Model Study ◽  
Superconducting Energy Gap ◽  
Wave Symmetry ◽  
Iron Based ◽  
Double Time ◽  
Gap Parameter

We present a theoretical model study of superconductivity for iron-based high-[Formula: see text] superconductors in s[Formula: see text]-wave symmetry, considering two degenerate orbitals and the electron hopping up to the third nearest neighbor as a two-orbital model. The analytic expression for the temperature dependence of the superconducting order parameter is derived by Zubarev’s technique of double time single particle Green’s function method and solved self-consistently. The effect of inter orbital hopping on the superconducting energy gap parameter and electronic specific heat is studied.

Ginzburg–Landau Equations for a d-Wave Superconductor with Paramagnetic Impurities

1998 ◽  
Vol 12 (10) ◽  
pp. 1069-1095 ◽  
Author(s):  
Wonkee Kim ◽  
C. S. Ting
Keyword(s):  
Transition Temperature ◽  
Born Approximation ◽  
Wave Interaction ◽  
London Penetration Depth ◽  
S Wave ◽  
Ginzburg Landau ◽  
Paramagnetic Impurities ◽  
Wave Symmetry ◽  
Ginzburg Landau Equations ◽  
D Wave

Ginzburg–Landau (GL) equations for a d-wave superconductor with a repulsive s-wave interaction between electrons in the presence of paramagnetic impurities are microscopically derived based on the Born approximation. The diagrammatic relationships for the impurity-averaged product of Green's functions are algebraically established. The effect of paramagnetic impurities on the transition temperature and the London penetration depth are discussed. GL equations for a superconductor with both s-wave and d-wave pairing interactions are also examined. We show that the transition temperature for a superconductor with an s-wave symmetry is suppressed twice as rapidly as that with a d-wave symmetry in the dilute impurity limit if the strength of the spin-non-flip scattering is much weaker than the spin-flip interaction.

TUNNELING SPECTROSCOPY OF THE ELECTRON-DOPED CUPRATE SUPERCONDUCTOR Pr2-xCexCuO4

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3175-3175
Author(s):  
A. BISWAS ◽  
P. FOURNIER ◽  
V. N. SMOLYANINOVA ◽  
H. BALCI ◽  
J. S. HIGGINS ◽  
...  
Keyword(s):  
Normal State ◽  
Cuprate Superconductors ◽  
Point Contact ◽  
Tunneling Spectroscopy ◽  
Pairing Symmetry ◽  
S Wave ◽  
Zero Bias ◽  
Wave Pairing ◽  
Wave Symmetry ◽  
D Wave

The properties of electron(n)-doped cuprate superconductors show significant deviations from those of their hold(p)-doped counterparts. Experiments prior to 2000 suggested an s-wave pairing symmetry as opposed to d-wave pairing symmetry in hole-doped cuprates. Recent experiments have suggested that n-doped cuprates have a d-wave pairing symmetry. However tunneling spectroscopy of these materials have not revealed a zero bias conductance peak (ZBCP), which is a classic signature of d-wave symmetry. We present the first tunneling spectroscopy data on n-doped Pr 2-x Ce x CuO 4 (PCCO) using point contact junctions which show a systematic evolution of the ZBCP. This method of junction fabrication is important as it allows the barrier strength between the normal and the superconducting electrodes to be varied. We show that this is essential to observing the ZBCP. The n-doped cuprates have a low Tc (~25 K ) and Hc2 (~10 T ). The low Hc2 enables us to obtain the normal state in PCCO at low temperatures. We have used this to probe the density of states in the normal state of PCCO. We observe an anomalous gap even in the normal state.1 This normal state gap (NSG) becomes smaller on the over-doped side. We discuss the behavior of this NSG in the context of the pseudogap which has been observed in hole-doped cuprates.

Pair Symmetry and Degree of Gap Depression at S-I Interfaces in HTS Josephson Junctions

1999 ◽  
Vol 13 (09n10) ◽  
pp. 1301-1306
Author(s):  
G. A. Ummarino ◽  
R. S. Gonnelli ◽  
C. Bravi ◽  
Masumi Inoue
Keyword(s):  
Josephson Junctions ◽  
Order Parameter ◽  
Reference Value ◽  
High Tc Superconductors ◽  
S Wave ◽  
General Reference ◽  
High Tc ◽  
Wave Symmetry ◽  
Set Up ◽  
D Wave

A new possible indirect way of testing pair symmetry in high-Tc superconductors has been set up. The degree of intrinsic gap depression at Superconductor-Insulator [S-I] interfaces required to match Ic(T)Rn(T) data in HTS Josephson junctions depends on the pair symmetry of the material itself, so that an higher fraction of d-wave symmetry for the order parameter requires less gap depression, while an higher fraction of s-wave corresponds to a larger degree of gap depression. In order to obtain a general reference value for the intrinsic amount of gap depression at S-I interfaces the de Gennes condition has been used, and resulting reduced Ic(T)Rn(T) data have been calculated in the framework of a mixed (s+id)-wave pair symmetry for the depressed order parameter ranging from pure s to pure d-wave. This model has been tentatively applied to two junctions' made of very different HTSs: YBCO and BKBO, yielding a result of almost pure d-wave for YBCO and of pure s-wave for BKBO.

scholarly journals Unusual symmetries of the order parameter in cuprates

2020 ◽  
Vol 2 (4) ◽  
pp. 207-212
Author(s):  
Tran Van Luong ◽  
Nguyen Thi Ngoc Nu
Keyword(s):  
High Temperature ◽  
Order Parameter ◽  
Cuprate Superconductors ◽  
High Temperature Superconductivity ◽  
Spin Fluctuation ◽  
High Temperature Superconductors ◽  
Coulomb Repulsion ◽  
Bcs Theory ◽  
S Wave ◽  
Wave Symmetry

The BCS superconducting theory, introduced by J. Bardeen, L. Cooper and R. Schriffer in 1957, succeeded in describing and satis-factorily explaining the nature of superconductivity for low-temperature superconductors. However, the BCS theory cannot explain the properties of high-temperature superconductors, discovered by J. G. Bednorz and K. A. Müller in 1986. Although scientists have found a lot of new superconductors and their transition temperatures are constantly increasing, most high-temperature superconductors are found by experiment and so far no theory can fully explain their properties. Many previous studies have suggested that the order parameter in high-temperature copper-based superconductors (cuprate superconductors - cuprates) is in the form of d-wave symmetry, but recent results show that the order parameter has an extended s-wave symmetry (extended s wave). Studying the symmetric forms of order parameters in cuprate can contribute to understanding the nature of high-temperature superconductivity. In this article, the authors present an overview of the development of high-temperature supercon-ductors over the past 30 years and explains unusual symmetries of the order parameter in copper-based superconductors. The com-petition of three coupling mechanisms of electrons in cuprates (the mechanism of coupling through coulomb repulsion, electron-phonon mechanism and spin-fluctuation mechanism) affects the unusual symmetry of the order parameter. The solution of the self-consistency equation in simple cases has been found and the ability to move the phase within the superconducting state has been shown.

GOSSAMER SUPERFLUID AND ANTIFERROMAGNETIC STATE OF COLD ATOMS IN OPTICAL LATTICES

2010 ◽  
Vol 24 (23) ◽  
pp. 2377-2386
Author(s):  
HONG-YI YU ◽  
FA-DI SUN ◽  
AN-CHUN JI
Keyword(s):  
Optical Lattice ◽  
Laser Field ◽  
Optical Lattices ◽  
Cold Atoms ◽  
Quantum Phase Transitions ◽  
Antiferromagnetic Phase ◽  
Experimental Protocol ◽  
S Wave ◽  
Wave Symmetry ◽  
New Phenomena

We propose a scheme to simulate the t–J–U model and investigate the quantum phase transitions using cold atoms confined in a two-dimensional optical lattice. By adjusting the parameters of external laser fields, we find a phase transition from antiferromagnetic phase to Gossamer superfluid. The Gossamer superfluid has a d-wave or mixed d- and s-wave symmetry, depending on the hopping parameters which can be adjusted by tuning the laser field. Experimental protocol to observe these new phenomena for future experiments has also been briefly discussed.

TUNNELING ASYMMETRY IN SUPERCONDUCTING Nd1Ba2Cu3Oy SINGLE CRYSTALS

1999 ◽  
Vol 13 (21) ◽  
pp. 735-742 ◽  
Author(s):  
A. T. WU ◽  
N. KOSHIZUKA ◽  
S. TANAKA
Keyword(s):  
Single Crystals ◽  
Scanning Tunneling Microscope ◽  
Theoretical Models ◽  
Charge Carriers ◽  
Scanning Tunneling ◽  
S Wave ◽  
Tunneling Microscope ◽  
Wave Symmetry ◽  
Atomically Flat ◽  
Pairing Potential

Clean, stable, and atomically flat (001) surfaces of the as-prepared Nd 1 Ba 2 Cu 3 O y (Nd123) single crystals have been investigated using a Low Temperature UltraHigh Vacuum Scanning Tunneling Microscope/Spectroscopy (STM/STS) system at 10 K. Several sets of highly reproducible STS data show the existence of an asymmetry in the tunneling spectra in superconducting Nd123 single crystals. The asymmetry is found to be intrinsic and can be explained by assuming that the pairing potential is a function of the kinetic energy of the charge carriers. The STS data are compared with the predictions of different theoretical models. The data on the (001) surfaces may be better fitted by assuming an S wave symmetry. Pure d(x2-y2) symmetry is ruled out.

scholarly journals Theory of superconductivity in strongly correlated electron systems

2018 ◽  
Vol 32 (23) ◽  
pp. 1850257 ◽  
Author(s):  
Chyh-Hong Chern
Keyword(s):  
Energy Gap ◽  
Electron System ◽  
Real Space ◽  
Pairing Symmetry ◽  
Attractive Potential ◽  
S Wave ◽  
Strongly Correlated Electron ◽  
Correlated Electron Systems ◽  
Correlated Electron ◽  
Wave Symmetry

In the correlated electron system with the pseudogap, full-gapped domains and Fermi-arced domains coexist. These domains are created by the quantum-fluctuated antiferromagnetic correlation that generates the short-ranged attractive potential to produce the Fermi arcs and the superconductivity. In the full-gapped domains, s-wave or [Formula: see text]-wave symmetry of the electron pairs is favored. In the Fermi-arced domains, only [Formula: see text]-wave symmetry of pairs is stable. Superconductivity of different pairing symmetry coexists in different domains as well. Different from the Cooper pairs, the correlated electrons pair up in the real space with an energy gap. Gapless states, on the contrary, hinder the development of superconductivity.

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