scholarly journals Holographic p-wave superconductivity from higher derivative theory

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
Yan Liu ◽  
Guoyang Fu ◽  
Hai-Li Li ◽  
Jian-Pin Wu ◽  
Xin Zhang
Keyword(s):  
Normal State ◽  
Ac Conductivity ◽  
Energy Gap ◽  
Low Frequency ◽  
High Derivative ◽  
Superconducting Phase ◽  
P Wave ◽  
S Wave ◽  
Higher Derivative ◽  
Superconducting Energy Gap

AbstractWe construct a holographic SU(2) p-wave superconductor model with Weyl corrections. The high derivative (HD) terms do not seem to spoil the generation of the p-wave superconducting phase. We mainly study the properties of AC conductivity, which is absent in holographic SU(2) p-wave superconductor with Weyl corrections. The conductivities in superconducting phase exhibit obvious anisotropic behaviors. Along y direction, the conductivity $$\sigma _{yy}$$ σ yy is similar to that of holographic s-wave superconductor. The superconducting energy gap exhibits a wide extension. For the conductivity $$\sigma _{xx}$$ σ xx along x direction, the behaviors of the real part in the normal state are closely similar to that of $$\sigma _{yy}$$ σ yy . However, the anisotropy of the conductivity obviously shows up in the superconducting phase. A Drude-like peak at low frequency emerges in $$Re\sigma _{xx}$$ R e σ xx once the system enters into the superconducting phase, regardless of the behaviors in normal state.

scholarly journals Analytical Study of the Holographic Superconductor from Higher Derivative Theory

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyan Wang ◽  
Dan Zhang ◽  
Guoyang Fu ◽  
Jian-Pin Wu
Keyword(s):  
Critical Temperature ◽  
Energy Gap ◽  
Mean Field ◽  
High Derivative ◽  
Temperature Limit ◽  
Holographic Superconductor ◽  
Higher Derivative ◽  
Superconducting Energy Gap ◽  
Perturbative Method ◽  
Coupling Parameters

In this paper, we analytically study the holographic superconductor models with the high derivative (HD) coupling terms. Using the Sturm-Liouville (S-L) eigenvalue method, we perturbatively calculate the critical temperature. The analytical results are in good agreement with the numerical results. It confirms that the perturbative method in terms of the HD coupling parameters is available. Along the same line, we analytically calculate the value of the condensation near the critical temperature. We find that the phase transition is second order with mean field behavior, which is independent of the HD coupling parameters. Then, in the low-temperature limit, we also calculate the conductivity, which is qualitatively consistent with the numerical one. We find that the superconducting energy gap is proportional to the value of the condensation. But we note that since the condensation changes with the HD coupling parameters, as the function of the HD coupling parameters, the superconducting energy gap follows the same change trend as that of the condensation.

scholarly journals Classifying Superconductivity in an Infinite-Layer Nickelate Nd0.8Sr0.2NiO2

2019 ◽  
Author(s):  
Evgueni Talantsev
Keyword(s):  
Energy Gap ◽  
Upper Critical Field ◽  
P Wave ◽  
London Penetration Depth ◽  
S Wave ◽  
Infinite Layer ◽  
Superconducting Energy Gap ◽  
Multiple Band ◽  
New Type ◽  
Current Densities

Recently Li et al (2019 Nature 572 624) discovered a new type of oxide superconductor Nd0.8Sr0.2NiO2 with Tc = 14 K. To classify superconductivity in this infinite-layer nickelate experimental upper critical field, Bc2(T), and the self-field critical current densities, Jc(sf,T), reported by Li et al (2019 Nature 572 624), are analysed in assumption of s-, d-, and p-wave pairing symmetries and single- and multiple-band superconductivity. Based on deduced the ground-state superconducting energy gap, Δ(0), the London penetration depth, λ(0), the relative jump in electronic specific heat at Tc, ΔC/C, and the ratio of 2Δ(0)/kBTc, we conclude that Nd0.8Sr0.2NiO2 is type-II high-κ weak-coupled single-band s-wave superconductor.

Retrieval of source-extent parameters and the interpretation of corner frequency

1983 ◽  
Vol 73 (6A) ◽  
pp. 1499-1511
Author(s):  
Paul Silver
Keyword(s):  
Body Wave ◽  
Amplitude Spectrum ◽  
Low Frequency ◽  
P Wave ◽  
Corner Frequency ◽  
S Wave ◽  
Dislocation Source ◽  
Statistical Measures ◽  
Dislocation Models ◽  
Planar Dislocation

Abstract A method is proposed for retrieving source-extent parameters from far-field body-wave data. At low frequency, the normalized P- or S-wave displacement amplitude spectrum can be approximated by |Ω^(r^,ω)| = 1 − τ2(r^)ω2/2 where r^ specifies a point on the focal sphere. For planar dislocation sources, τ2(r^) is linearly related to statistical measures of source dimension, source duration, and directivity. τ2(r^) can be measured as the curvature of |Ω^(r^,ω)| at ω = 0 or the variance of the pulse Ω^(r^,t). The quantity ωc=2τ−1(r^) is contrasted with the traditional corner frequency ω0, defined as the frequency at the intersection of the low- and high-frequency trends of |Ω^(r^,ω)|. For dislocation models without directivity, ωc(P) ≧ ωc(S) for any r^. A mean corner frequency defined by averaging τ2(r^) over the focal sphere, ω¯c=2<τ2(r^)>−1/2, satisfies ωc(P) > ωc(S) for any dislocation source. This behavior is not shared by ω0. It is shown that ω0 is most sensitive to critical times in the rupture history of the source, whereas ωc is determined by the basic parameters of source extent. Evidence is presented that ωc is the corner frequency measured on actual seismograms. Thus, the commonly observed corner frequency shift (P-wave corner greater than the S-wave corner), now viewed as a shift in ωc is simply a result of spatial finiteness and is expected to be a property of any dislocation source. As a result, the shift cannot be used as a criterion for rejecting particular dislocation models.

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.

Normal-state reflectivity and superconducting energy-gap measurement ofLa2−xSrxCuO4

1987 ◽  
Vol 36 (10) ◽  
pp. 5275-5278 ◽  
Author(s):  
Z. Schlesinger ◽  
R. T. Collins ◽  
M. W. Shafer ◽  
E. M. Engler
Keyword(s):  
Normal State ◽  
Energy Gap ◽  
Gap Measurement ◽  
Superconducting Energy Gap

PROPELLER NOISE FROM A LIGHT AIRCRAFT FOR LOW-FREQUENCY MEASUREMENTS OF THE SPEED OF SOUND IN A MARINE SEDIMENT

2002 ◽  
Vol 10 (04) ◽  
pp. 445-464 ◽  
Author(s):  
MICHAEL J. BUCKINGHAM ◽  
ERIC M. GIDDENS ◽  
FERNANDO SIMONET ◽  
THOMAS R. HAHN
Keyword(s):  
Water Column ◽  
Speed Of Sound ◽  
Low Frequency ◽  
Deep Ocean ◽  
Fine Sand ◽  
P Wave ◽  
Difference Frequency ◽  
S Wave ◽  
Low Frequencies ◽  
La Jolla

The sound from a light aircraft in flight is generated primarily by the propeller, which produces a sequence of harmonics in the frequency band between about 80 Hz and 1 kHz. Such an airborne sound source has potential in underwater acoustics applications, including inversion procedures for determining the wave properties of marine sediments. A series of experiments has recently been performed off the coast of La Jolla, California, in which a light aircraft was flown over a sensor station located in a shallow (approximately 15 m deep) ocean channel. The sound from the aircraft was monitored with a microphone above the sea surface, a vertical array of eight hydrophones in the water column, and two sensors, a hydrophone and a bender intended for detecting shear waves, buried 75 cm deep in the very-fine-sand sediment. The propeller harmonics were detected on all the sensors, although the s-wave was masked by the p-wave on the buried bender. Significant Doppler shifts of the order of 17%, were observed on the microphone as the aircraft approached and departed from the sensor station. Doppler shifting was also evident in the hydrophone data from the water column and the sediment, but to a lesser extent than in the atmosphere. The magnitude of the Doppler shift depends on the local speed of sound in the medium in which the sensor is located. A technique is described in which the Doppler difference frequency between aircraft approach and departure is used to determine the speed of sound at low-frequencies (80 Hz to 1 kHz) in each of the three environments, the atmosphere, the ocean and the sediment. Several experimental results are presented, including the speed of sound in the very fine sand sediment at a nominal frequency of 600 Hz, which was found from the Doppler difference frequency of the seventh propeller harmonic to be 1617 m/s.

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.

scholarly journals An Evaluation of Strong-Motion Parameters at the S-net Ocean-Bottom Seismograph Sites Near the Kanto Basin for Earthquake Early Warning

2021 ◽  
Vol 9 ◽  
Author(s):  
Yadab P. Dhakal ◽  
Takashi Kunugi
Keyword(s):  
Early Warning ◽  
Low Frequency ◽  
Strong Motion ◽  
Earthquake Early Warning ◽  
P Wave ◽  
Japan Trench ◽  
S Wave ◽  
Earthquake Disaster ◽  
Strong Motion Records ◽  
Kanto Basin

We analyzed strong-motion records at the ground and borehole in and around the Kanto Basin and the seafloor in the Japan Trench area from three nearby offshore earthquakes of similar magnitudes (Mw 5.8–5.9). The seafloor strong-motion records were obtained from S-net, which was established to enhance tsunami and earthquake early warnings after the 2011 great Tohoku-oki earthquake disaster. The borehole records were obtained from MeSO-net, a dense network of seismometers installed at a depth of 20 m in the Tokyo metropolitan area. The ground records were obtained from the K-NET and KiK-net networks, established after the 1995 great Hanshin-Awaji earthquake disaster. The MeSO-net and S-net stations record the shakings continuously, while the K-NET and KiK-net records are based on triggering thresholds. It is crucial to evaluate the properties of strong motions recorded by the S-net for earthquake early warning (EEW). This paper compared the peak ground accelerations (PGAs) and peak ground velocities (PGVs) between the S-net and K-NET/KiK-net stations. Because the MeSO-net records were from the borehole, we compared the PGAs and significant durations of the low-frequency motions (0.1–0.5 Hz) between the S-net and MeSO-net stations from identical record lengths. We found that the horizontal PGAs and PGVs at the S-net sites were similar to or larger than the K-NET/KiK-net sites for the S wave. In contrast, the vertical PGAs and PGVs at the S-net sites were similar to or smaller than those at the K-NET/KiK-net sites for the S wave. Particularly, the PGAs and PGVs for the P-wave parts on the vertical-component records of S-net were, on average, much smaller than those of K-NET/KiK-net records. The difference was more evident in the PGAs. The average ratios of S-wave horizontal to vertical PGAs were about 2.5 and 5 for the land and S-net sites, respectively. The low-frequency PGAs at the S-net sites were similar to or larger than those of the MeSO-net borehole records. The significant durations between the two-networks low-frequency records were generally comparable. Quantification of the results from a larger dataset may contribute to ground-motion prediction for EEW and the design of the offshore facilities.

A PROPOSED NEW MEASUREMENT OF THE SUPERCONDUCTING GAP IN YBa2Cu3O7

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3290-3293 ◽  
Author(s):  
G. L. ZHAO ◽  
D. BAGAYOKO
Keyword(s):  
Fermi Surface ◽  
Density Functional ◽  
Energy Gap ◽  
Interaction Matrix ◽  
Superconducting Gap ◽  
S Wave ◽  
Minor Variation ◽  
High Tc ◽  
Symmetry Properties ◽  
Superconducting Energy Gap

The superconducting energy gap of YBa 2 Cu 3 O 7 (YBCO) varies strongly with [Formula: see text] and from a sheet of the Fermi surface to another. The strong anisotropic superconducting gap in high Tc materials such as YBCO has led to conflicting d-wave and s-wave interpretations. We have utilized electronic wave functions from the ab-initio density functional calculation and the related electron-phonon interaction matrix elements for the calculation of the superconducting gap values of YBCO. We have found that the superconducting gap on one sheet of the Fermi surface around S-point only shows a minor variation from about 18 meV to 25 meV. Especially, there is no node on this sheet of the Fermi surface around the S-point. We propose a new test measurement of the superconducting gap of YBCO on this sheet of the Fermi surface around the S-point in the Brillouin zone. This measurement is expected to shed light on the gap symmetry properties of high Tc superconductors.

Determination of formation shear attenuation from dipole sonic log data

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. D73-D79 ◽  
Author(s):  
Qiaomu Qi ◽  
Arthur C. H. Cheng ◽  
Yunyue Elita Li
Keyword(s):  
Reservoir Characterization ◽  
Wave Attenuation ◽  
Synthetic Data ◽  
Low Frequency ◽  
P Wave ◽  
Flexural Wave ◽  
S Wave ◽  
Additional Energy ◽  
Log Data ◽  
Sonic Log

ABSTRACT Formation S-wave attenuation, when combined with compressional attenuation, serves as a potential hydrocarbon indicator for seismic reservoir characterization. Sonic flexural wave measurements provide a direct means for obtaining the in situ S-wave attenuation at log scale. The key characteristic of the flexural wave is that it propagates at the formation shear slowness and experiences shear attenuation at low frequency. However, in a fast formation, the dipole log consists of refracted P- and S-waves in addition to the flexural wave. The refracted P-wave arrives early and can be removed from the dipole waveforms through time windowing. However, the refracted S-wave, which is often embedded in the flexural wave packet, is difficult to separate from the dipole waveforms. The additional energy loss associated with the refracted S-wave results in the estimated dipole attenuation being higher than the shear attenuation at low frequency. To address this issue, we have developed a new method for accurately determining the formation shear attenuation from the dipole sonic log data. The method uses a multifrequency inversion of the frequency-dependent flexural wave attenuation based on energy partitioning. We first developed our method using synthetic data. Application to field data results in a shear attenuation log that is consistent with lithologic interpretation of other available logs.

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