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

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.

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

Journal of Superconductivity ◽

10.1007/bf00724578 ◽

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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Superconducting energy gap of NbS2

Canadian Journal of Physics ◽

10.1139/p84-107 ◽

1984 ◽

Vol 62 (8) ◽

pp. 776-779 ◽

Cited By ~ 12

Author(s):

R. J. Kennedy ◽

B. P. Clayman

Keyword(s):

Magnetic Susceptibility ◽

Transition Temperature ◽

Energy Gap ◽

Far Infrared ◽

The Novel ◽

Superconducting Transition ◽

Small Particles ◽

Energy Gaps ◽

Superconducting Energy Gap ◽

Novel Method

The superconducting energy gaps of small particles (1–10 μm) of 2H–NbS2 and 2H–NbSe2 have been measured by far-infrared (FIR) transmission spectroscopy. Comparison of these results with previous FIR measurements made on millimetre-size single crystals of 2H–NbSe2 validates the use of the novel method of sample preparation used here. Comparison of the gap frequencies (νg) with the superconducting transition temperature (Tc) determined by magnetic susceptibility measurements indicates that 2H–NbS2, unlike 2H–NbSe2, exhibits non-Bardeen–Cooper–Schrieffer (BCS)-like behaviour, with hνg/kTc = 2.3.

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Inhomogeneous Superconductivity in Organic and Related Superconductors

Crystals ◽

10.3390/cryst8070285 ◽

2018 ◽

Vol 8 (7) ◽

pp. 285 ◽

Cited By ~ 5

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.

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Superconducting energy gap from break-junction tunneling spectroscopy in the ternary silicide CaAlSi

Physical Review B ◽

10.1103/physrevb.76.104508 ◽

2007 ◽

Vol 76 (10) ◽

Cited By ~ 6

Author(s):

S. Kuroiwa ◽

T. Takasaki ◽

T. Ekino ◽

J. Akimitsu

Keyword(s):

Energy Gap ◽

Tunneling Spectroscopy ◽

Break Junction ◽

Superconducting Energy Gap ◽

Ternary Silicide

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

Physical Review B ◽

10.1103/physrevb.69.100501 ◽

2004 ◽

Vol 69 (10) ◽

Cited By ~ 6

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

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High Tc Oxide Superconductors

MRS Bulletin ◽

10.1557/s0883769400059479 ◽

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.

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