scholarly journals Inhomogeneous Superconductivity in Organic and Related Superconductors

Crystals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 285 ◽  
Author(s):  
Charles Agosta
Keyword(s):  
Low Temperatures ◽  
Energy Gap ◽  
Measurement Methods ◽  
Superconducting Order Parameter ◽  
Organic Superconductors ◽  
New Materials ◽  
Superconducting Energy Gap ◽  
Anisotropic Superconductors ◽  
High Fields ◽  
Inhomogeneous Superconductivity

Evidence of inhomogeneous superconductivity, in this case superconductivity with a spatially modulated superconducting order parameter, has now been found in many materials and by many measurement methods. Although the evidence is strong, it is circumstantial in the organic superconductors, scant in the pnictides, and complex in the heavy Fermions. However, it is clear some form of exotic superconductivity exists at high fields and low temperatures in many electronically anisotropic superconductors. The evidence is reviewed in this article, and examples of similar measurements are compared across different families of superconductors. An effort is made to find a consistent way to measure the superconducting energy gap across all materials, and use this value to predict the Clogston–Chandrasakhar paramagnetic limit Hp. Methods for predicting the existence of inhomogeneous superconductivity are shown to work for the organic superconductors, and then used to suggest new materials to study.

scholarly journals Momentum-resolved superconducting energy gaps of Sr2RuO4 from quasiparticle interference imaging

2020 ◽  
Vol 117 (10) ◽  
pp. 5222-5227 ◽  
Author(s):  
Rahul Sharma ◽  
Stephen D. Edkins ◽  
Zhenyu Wang ◽  
Andrey Kostin ◽  
Chanchal Sow ◽  
...  
Keyword(s):  
Knight Shift ◽  
Energy Gap ◽  
Space Structure ◽  
Superconducting Order Parameter ◽  
Temperature Dependent ◽  
High Precision Measurement ◽  
Quasiparticle Interference ◽  
Energy Gaps ◽  
Superconducting Energy Gap ◽  
Intense Research

Sr2RuO4 has long been the focus of intense research interest because of conjectures that it is a correlated topological superconductor. It is the momentum space (k-space) structure of the superconducting energy gap Δi(k) on each band i that encodes its unknown superconducting order parameter. However, because the energy scales are so low, it has never been possible to directly measure the Δi(k) of Sr2RuO4. Here, we implement Bogoliubov quasiparticle interference (BQPI) imaging, a technique capable of high-precision measurement of multiband Δi(k). At T = 90 mK, we visualize a set of Bogoliubov scattering interference wavevectors qj:j=1−5 consistent with eight gap nodes/minima that are all closely aligned to the (±1,±1) crystal lattice directions on both the α and β bands. Taking these observations in combination with other very recent advances in directional thermal conductivity [E. Hassinger et al., Phys. Rev. X 7, 011032 (2017)], temperature-dependent Knight shift [A. Pustogow et al., Nature 574, 72–75 (2019)], time-reversal symmetry conservation [S. Kashiwaya et al., Phys. Rev B, 100, 094530 (2019)], and theory [A. T. Rømer et al., Phys. Rev. Lett. 123, 247001 (2019); H. S. Roising, T. Scaffidi, F. Flicker, G. F. Lange, S. H. Simon, Phys. Rev. Res. 1, 033108 (2019); and O. Gingras, R. Nourafkan, A. S. Tremblay, M. Côté, Phys. Rev. Lett. 123, 217005 (2019)], the BQPI signature of Sr2RuO4 appears most consistent with Δi(k) having dx2−y2(B1g) symmetry.

scholarly journals Phonon self-energy effects in the superconducting energy gap ofMgB2point-contact spectra

2004 ◽  
Vol 69 (10) ◽  
Author(s):  
I. K. Yanson ◽  
S. I. Beloborod’ko ◽  
Yu. G. Naidyuk ◽  
O. V. Dolgov ◽  
A. A. Golubov
Keyword(s):  
Energy Gap ◽  
Self Energy ◽  
Superconducting Energy Gap

High Tc Oxide Superconductors

MRS Bulletin ◽  
1990 ◽  
Vol 15 (6) ◽  
pp. 31-33
Author(s):  
M. Brian Maple
Keyword(s):  
Physical Properties ◽  
Energy Gap ◽  
Vortex State ◽  
Oxide Superconductors ◽  
High Tc ◽  
Superconducting Energy Gap ◽  
Consistent Picture ◽  
Novel Processing ◽  
Processing Techniques

This issue of the MRS BULLETIN is devoted to high Tc superconductivity. It is the sequel to a previous series of articles on the same subject which appeared in the MRS BULLETIN in January 1989. While the articles in the January 1989 issue emphasized the families of high Tc superconducting oxides known at that rime, as well as novel processing techniques and thin films, the papers in this issue focus on the physical properties of high Tc oxide superconductors.The quality of polycrystalline and single-crystal bulk and thin-film materials has improved to the point where researchers can now make reliable measurements of many physical properties representative of the intrinsic behavior of these materials. As a result, a broad spectrum of important issues such as the nature of the electronic structure, the type of superconducting electron pairing, the magnitude and temperature dependence of the superconducting energy gap, the behavior of fluxoids in the vortex state, etc., can be addressed meaningfully. Presently emerging is a consistent picture of the physical properties of the high Tc oxides, which will form the foundation to eventually developing an appropriate theory for the normal and superconducting states of these remarkable materials.

scholarly journals Higher derivatives driven symmetry breaking in holographic superconductors

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Hai-Li Li ◽  
Guoyang Fu ◽  
Yan Liu ◽  
Jian-Pin Wu ◽  
Xin Zhang
Keyword(s):  
High Temperature Superconductor ◽  
Energy Gap ◽  
Coupling Term ◽  
Holographic Superconductor ◽  
Complex Scalar ◽  
Holographic Superconductors ◽  
Higher Derivative ◽  
Superconducting Energy Gap ◽  
Higher Derivatives ◽  
Complex Scalar Field

Abstract In this paper, we construct a novel holographic superconductor from higher derivative (HD) gravity involving a coupling between the complex scalar field and the Weyl tensor. This HD coupling term provides a near horizon effective mass squared, which can violates IR Breitenlohner–Freedman (BF) bound by tuning the HD coupling and induces the instability of black brane such that the superconducting phase transition happens. We also study the properties of the condensation and the conductivity in the probe limit. We find that a wider extension of the superconducting energy gap ranging from 4.6 to 10.5 may provide a novel platform to model and interpret the phenomena in the real materials of high temperature superconductor.

BCS temperature-dependent superconducting energy gap in domain boundaries of melt-textured YBa2Cu3O7

1994 ◽  
Vol 7 (2) ◽  
pp. 409-414
Author(s):  
Moises Levy ◽  
Zheng -Xiao Li ◽  
Bimal K. Sarma ◽  
S. Salem-Sugui ◽  
Donglu Shi
Keyword(s):  
Energy Gap ◽  
Temperature Dependent ◽  
Superconducting Energy Gap ◽  
Domain Boundaries
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