scholarly journals Influence of apical oxygen on the extent of in-plane exchange interaction in cuprate superconductors

2017 ◽  
Vol 13 (12) ◽  
pp. 1201-1206 ◽  
Author(s):  
Y. Y. Peng ◽  
G. Dellea ◽  
M. Minola ◽  
M. Conni ◽  
A. Amorese ◽  
...  
Keyword(s):  
Exchange Interaction ◽  
Cuprate Superconductors ◽  
Apical Oxygen

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.

INDIRECT EXCHANGE INTERACTION IN Hg1-xMnxTe AND Cd1-xMnxTe ALLOYS

1980 ◽  
Vol 41 (C5) ◽  
pp. C5-289-C5-292 ◽  
Author(s):  
C. Lewiner ◽  
J. A. Gaj ◽  
G. Bastard
Keyword(s):  
Exchange Interaction ◽  
Indirect Exchange Interaction ◽  
Indirect Exchange

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

Two-electron exchange interaction in the quasimolecular systems with long-range dipole potential

2015 ◽  
Vol 38 (0) ◽  
pp. 45-55
Author(s):  
О. Мирославович Карбованець ◽  
Мирослав Іванович Карбованець ◽  
Володимир Юрійович Лазур ◽  
М. В. Хома
Keyword(s):  
Exchange Interaction ◽  
Long Range ◽  
Electron Exchange ◽  
Dipole Potential ◽  
Electron Exchange Interaction

Excitonic quasimolecules containing of two quantum dots

2016 ◽  
pp. 4024-4028 ◽  
Author(s):  
Sergey I. Pokutnyi ◽  
Wlodzimierz Salejda
Keyword(s):  
Quantum Dots ◽  
Binding Energy ◽  
Exchange Interaction ◽  
Coulomb Interaction ◽  
Silicate Glass ◽  
Glass Matrix ◽  
Silicate Glass Matrix

The possibility of occurrence of the excitonic  quasimolecule formed of spatially separated electrons and holes in a nanosystem that consists  of  CuO quantum dots synthesized in a silicate glass matrix. It is shown that the major contribution to the excitonic quasimolecule binding energy is made by the energy of the exchange interaction of electrons with holes and this contribution is much more substantial than the contribution of the energy of Coulomb interaction between the electrons and holes.

Electronic properties of quasi two-dimensional transition metals chalcogenides with low-dimensional magnetism

Doklady BGUIR ◽  
2020 ◽  
Vol 18 (7) ◽  
pp. 87-95
Author(s):  
M. S. Baranava ◽  
P. A. Praskurava
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Exchange Interaction ◽  
Electronic Properties ◽  
Metal Atom ◽  
Transition Metal Atom ◽  
Two Dimensional ◽  
Transition Metal Atoms ◽  
Ground Magnetic ◽  
Low Dimensional

The search for fundamental physical laws which lead to stable high-temperature ferromagnetism is an urgent task. In addition to the already synthesized two-dimensional materials, there remains a wide list of possible structures, the stability of which is predicted theoretically. The article suggests the results of studying the electronic properties of MAX3 (M = Cr, Fe, A = Ge, Si, X = S, Se, Te) transition metals based compounds with nanostructured magnetism. The research was carried out using quantum mechanical simulation in specialized VASP software and calculations within the Heisenberg model. The ground magnetic states of twodimensional MAX3 and the corresponding energy band structures are determined. We found that among the systems under study, CrGeTe3 is a semiconductor nanosized ferromagnet. In addition, one is a semiconductor with a bandgap of 0.35 eV. Other materials are antiferromagnetic. The magnetic moment in MAX3 is localized on the transition metal atoms: in particular, the main one on the d-orbital of the transition metal atom (and only a small part on the p-orbital of the chalcogen). For CrGeTe3, the exchange interaction integral is calculated. The mechanisms of the formation of magnetic order was established. According to the obtained exchange interaction integrals, a strong ferromagnetic order is formed in the semiconductor plane. The distribution of the projection density of electronic states indicates hybridization between the d-orbital of the transition metal atom and the p-orbital of the chalcogen. The study revealed that the exchange interaction by the mechanism of superexchange is more probabilistic.

Sign in / Sign up

Export Citation Format

Share Document