Fluctuation effects in the microwave conductivity of cuprate superconductors

1999 ◽  
Vol 59 (2) ◽  
pp. 1528-1537 ◽  
Author(s):  
J. R. Waldram ◽  
D. M. Broun ◽  
D. C. Morgan ◽  
R. Ormeno ◽  
A. Porch
Keyword(s):  
Cuprate Superconductors ◽  
Microwave Conductivity ◽  
Fluctuation Effects

Anomalous microwave conductivity due to collective transport in the pseudogap state of cuprate superconductors

2002 ◽  
Vol 65 (13) ◽  
Author(s):  
C. Kusko ◽  
Z. Zhai ◽  
N. Hakim ◽  
R. S. Markiewicz ◽  
S. Sridhar ◽  
...  
Keyword(s):  
Cuprate Superconductors ◽  
Microwave Conductivity ◽  
Pseudogap State ◽  
Collective Transport

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

Superconductivity Mechanism of Non-Cuprate Superconductors

1993 ◽  
Vol 20 (3) ◽  
pp. 269-274
Author(s):  
Chao-Fan Yu ◽  
Zhen-Qing Yang ◽  
Guo-Zhu He
Keyword(s):  
Cuprate Superconductors

STABLE hc/e VORTICES IN SUPERCONDUCTORS WITH SPIN-CHARGE SEPARATION

1992 ◽  
Vol 06 (05n06) ◽  
pp. 509-526
Author(s):  
Subir Sachdev
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Normal State ◽  
Phenomenological Model ◽  
Charge Separation ◽  
Cuprate Superconductors ◽  
Superconducting Phase ◽  
Low Energy ◽  
Large N ◽  
Normal State Properties

A phenomenological model, F, of the superconducting phase of systems with spin-charge separation and antiferromagnetically induced pairing is studied. Above Hc1, magnetic flux can always pierce the superconductor in vortices with flux hc/2e, but regimes are found in which vortices with flux hc/e are preferred. Little-Park and other experiments, which examine periodicities with a varying magnetic field, always observe a period of hc/2e. The low energy properties of a symplectic large-N expansion of a model of the cuprate superconductors are argued to be well described by F. This analysis and some normal state properties of the cuprates suggest that hc/e vortices should be stable at the lowest dopings away from the insulating state at which superconductivity first occurs.

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