scholarly journals Characteristic energy of the nematic-order state and its connection to enhancement of superconductivity in cuprate superconductors

2021 ◽  
Vol 104 (22) ◽  
Author(s):  
Zhangkai Cao ◽  
Xingyu Ma ◽  
Yiqun Liu ◽  
Huaiming Guo ◽  
Shiping Feng
Keyword(s):  
Cuprate Superconductors ◽  
Characteristic Energy ◽  
Nematic Order ◽  
Enhancement Of Superconductivity ◽  
Order State

scholarly journals Intertwined Vestigial Order in Quantum Materials: Nematicity and Beyond

2019 ◽  
Vol 10 (1) ◽  
pp. 133-154 ◽  
Author(s):  
Rafael M. Fernandes ◽  
Peter P. Orth ◽  
Jörg Schmalian
Keyword(s):  
Order Parameter ◽  
Cuprate Superconductors ◽  
Primary Phase ◽  
Nematic Order ◽  
Unconventional Superconductors ◽  
Underlying Principle ◽  
Microscopic Models ◽  
Quantum Materials ◽  
Component Order

A hallmark of the phase diagrams of quantum materials is the existence of multiple electronic ordered states, which, in many cases, are not independent competing phases, but instead display a complex intertwinement. In this review, we focus on a particular realization of intertwined orders: a primary phase characterized by a multi-component order parameter and a fluctuation-driven vestigial phase characterized by a composite order parameter. This concept has been widely employed to elucidate nematicity in iron-based and cuprate superconductors. Here we present a group-theoretical framework that extends this notion to a variety of phases, providing a classification of vestigial orders of unconventional superconductors and density waves. Electronic states with scalar and vector chiral order, spin-nematic order, Ising-nematic order, time-reversal symmetry-breaking order, and algebraic vestigial order emerge from one underlying principle. The formalism provides a framework to understand the complexity of quantum materials based on symmetry, largely without resorting to microscopic models.

Doping and energy dependences of thermal conductivity in cuprate superconductors

2017 ◽  
Vol 31 (27) ◽  
pp. 1750344 ◽  
Author(s):  
Chunsheng Ma ◽  
Rui Qi ◽  
Feng Yuan ◽  
Shaou Chen ◽  
Huaisong Zhao
Keyword(s):  
Thermal Conductivity ◽  
Doping Concentration ◽  
Cuprate Superconductors ◽  
The Other ◽  
Characteristic Peak ◽  
Characteristic Energy ◽  
Doping Dependence ◽  
Pseudogap Phase ◽  
In Doping ◽  
The One

By considering the pseudogap effect, the doping and energy dependences of thermal conductivity in cuprate superconductors are studied. Our results show that the thermal conductivity as a function of energy exhibits a characteristic peak from underdoping to overdoping due to the presence of the pseudogap in pseudogap phase of cuprate superconductors. The thermal conductivity is strongly doping dependent. On the one hand, with increasing doping concentration, the weight of thermal conductivity increases quickly, especially the residual thermal conductivity which is in qualitative agreement with the experimental data. On the other hand, the characteristic energy corresponding to the position of the characteristic peak decreases monotonically upon increasing doping concentration, and it scales with the doping dependence of pseudogap. In particular, we have studied the doping dependence of the ratio of quasiparticle velocities normal and tangential to the Fermi surface at the nodes [Formula: see text]. It is shown that [Formula: see text] increases with the increase of doping concentration. Moreover, we explain that both the residual thermal conductivity and [Formula: see text] increase rapidly upon the increase in doping concentration in heavily overdoped cuprate superconductors.

Nature of charge order in cuprate superconductors

2016 ◽  
Vol 30 (13) ◽  
pp. 1642005
Author(s):  
Shiping Feng ◽  
Deheng Gao ◽  
Huaisong Zhao
Keyword(s):  
Hot Spots ◽  
Cuprate Superconductors ◽  
Charge Order ◽  
Theoretical Work ◽  
Fermi Arc ◽  
Self Energy ◽  
Fermi Arcs ◽  
Arc Instability ◽  
Microscopic Origin ◽  
Order State

The recently discovered charge order is an intrinsic and universal property of cuprate superconductors, however, its microscopic origin remains debated. Here we review briefly the theoretical work about the nature of charge order in cuprate superconductors. In particular, we show that the electron self-energy obliterates the electron Fermi surface around the antinodal region, leaving behind disconnected Fermi arcs located around the nodal region. The charge-order state on the other hand is driven by the Fermi-arc instability, with a characteristic wavevector corresponding to the hot spots of the Fermi arcs rather than the antinodal nesting vector. Since the pseudogap emanates from the electron self-energy, the Fermi arc, charge order, and pseudogap in cuprate superconductors are intimately related each other.

Correlation between charge-order state and next nearest-neighbor hopping in electron-doped cuprate superconductors

2018 ◽  
Vol 32 (17) ◽  
pp. 1840027 ◽  
Author(s):  
Yingping Mou ◽  
Shiping Feng
Keyword(s):  
Wave Vector ◽  
Cuprate Superconductors ◽  
Nearest Neighbor ◽  
Charge Order ◽  
Order State

Within the framework of the t-t[Formula: see text]J model, the evolution of the charge-order state with the next nearest-neighbor (NN) hopping in the electron-doped cuprate superconductors is studied. It is shown that although the magnitude of the charge-order wave vector increases with the increase of the next NN hopping in the hole-doped case, the charge-order wave vector in the electron-doped side decreases with the increase of the next NN hopping, reflecting an asymmetric next NN hopping dependence of the charge-order state between the hole- and electron-doped cuprate superconductors.

Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

1990 ◽  
Vol 48 (2) ◽  
pp. 56-57
Author(s):  
C P Scott ◽  
A J Craven ◽  
C J Gilmore ◽  
A W Bowen
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Simple Form ◽  
Single Scattering ◽  
Low Loss ◽  
Characteristic Energy ◽  
Normal Method ◽  
Fitting In ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

Quantitative structure determination of interfaces through Z-contrast imaging and electron energy loss spectroscopy

1996 ◽  
Vol 54 ◽  
pp. 104-105
Author(s):  
S. J. Pennycook ◽  
P. D. Nellist ◽  
N. D. Browning ◽  
P. A. Langjahr ◽  
M. Rühle
Keyword(s):  
Grain Boundaries ◽  
Cuprate Superconductors ◽  
Structure Refinement ◽  
3D Structure ◽  
Real Space ◽  
Contrast Imaging ◽  
Coordination Polyhedra ◽  
Burgers Vector ◽  
Z Contrast ◽  
Contrast Image

The simultaneous use of Z-contrast imaging with parallel detection EELS in the STEM provides a powerful means for determining the atomic structure of grain boundaries. The incoherent Z-contrast image of the high atomic number columns can be directly inverted to their real space arrangement, without the use of preconceived structure models. Positions and intensities may be accurately quantified through a maximum entropy analysis. Light elements that are not visible in the Z-contrast image can be studied through EELS; their coordination polyhedra determined from the spectral fine structure. It even appears feasible to contemplate 3D structure refinement through multiple scattering calculations.The power of this approach is illustrated by the recent study of a series of SrTiC>3 bicrystals, which has provided significant insight into some of the basic issues of grain boundaries in ceramics. Figure 1 shows the structural units deduced from a set of 24°, 36° and 65° symmetric boundaries, and 24° and 45° asymmetric boundaries. It can be seen that apart from unit cells and fragments from the perfect crystal, only three units are needed to construct any arbitrary tilt boundary. For symmetric boundaries, only two units are required, each having the same Burgers, vector of a<100>. Both units are pentagons, on either the Sr or Ti sublattice, and both contain two columns of the other sublattice, imaging in positions too close for the atoms in each column to be coplanar. Each column was therefore assumed to be half full, with the pair forming a single zig-zag column. For asymmetric boundaries, crystal geometry requires two types of dislocations; the additional unit was found to have a Burgers’ vector of a<110>. Such a unit is a larger source of strain, and is especially important to the transport characteristics of cuprate superconductors. These zig-zag columns avoid the problem of like-ion repulsion; they have also been seen in TiO2 and YBa2Cu3O7-x and may be a general feature of ionic materials.

CRITICAL STATE MODEL FOR CUPRATE SUPERCONDUCTORS

1988 ◽  
Vol 49 (C8) ◽  
pp. C8-2231-C8-2232
Author(s):  
A. M. Portis ◽  
M. Stalder ◽  
G. Stefanicki ◽  
F. Waldner ◽  
M. Warden
Keyword(s):  
Critical State ◽  
Cuprate Superconductors ◽  
Critical State Model ◽  
State Model
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