scholarly journals Influence of Uniform Compression on the Temperature Dependence of the Pseudogap of Medium-Praseodymium-Doped Y1−xPrxBa2Cu3O7−δ Single Crystals

2021 ◽  
Author(s):  
G. Ya. Khadzhai ◽  
A. Chroneos ◽  
Ι. L. Goulatis ◽  
S. N. Kamchatnaya ◽  
A. L. Chikina ◽  
...  
Keyword(s):  
Field Theory ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Mean Field Theory ◽  
Applied Pressure ◽  
Mean Field ◽  
Excess Conductivity ◽  
Uniform Compression ◽  
Exponential Temperature Dependence ◽  
The Mean

AbstractThe effect of high pressure on the conductivity in the basal plane of HTSC single crystals of Y0.77Pr0.23Ba2Cu3O7−δ is investigated. It has been established that the excess conductivity, Δσ(T), of these single crystals in a wide temperature range Tf < T < T* can be described by an exponential temperature dependence. The description of the excess conductivity using the relation Δσ ~ (1 − T/T*)exp(Δ*ab/T) can be interpreted in terms of the mean-field theory, where T* is represented as the temperature pseudogap opening, and the temperature dependence of the pseudogap (PG) is satisfactorily described in the framework of the BCS-BEC crossover theory. An increase in the applied pressure leads to the effect of narrowing the temperature interval for the realization of the PG-regime, thereby expanding the region of the linear dependence ρ(T) in the ab-plane.

INFLUENCE OF HIGH PRESSURE ON THE TEMPERATURE-DEPENDENCE OF THE PSEUDO-GAP IN OXYGEN DEFICIENT YBa2Cu3O7-δ SINGLE CRYSTALS

2010 ◽  
Vol 24 (22) ◽  
pp. 2295-2301 ◽  
Author(s):  
R. V. VOVK ◽  
A. A. ZAVGORODNIY ◽  
M. A. OBOLENSKII ◽  
I. L. GOULATIS ◽  
A. CHRONEOS ◽  
...  
Keyword(s):  
High Pressure ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Mean Field Theory ◽  
Applied Pressure ◽  
Mean Field ◽  
Einstein Condensate ◽  
Excess Conductivity ◽  
Bose Einstein Condensate ◽  
Exponential Temperature Dependence

The influence of high pressure on the conductivity in the ab-plane of the oxygen deficient YBa 2 Cu 3 O 7-δ single crystals is investigated. It is determined that excess conductivity Δσ(T) in the YBa 2 Cu 3 O 7-δ single crystals in a wide temperature interval (Tc < T < T*, where Tc is the critical temperature and T* is the temperature that the PG regime begins) obeys an exponential temperature-dependence. The description of the excess conductivity with [Formula: see text]) can be interpreted in terms of mean field theory. The temperature-dependence of the pseudo-gap is well described in the framework of the Bardeen–Cooper–Schrieffer (BCS) to the Bose–Einstein condensate (BEC) crossover theory. Increasing the applied pressure leads to the effect of narrowing the temperature range of implementation of the PG regime, thus extending the area of linear ρ(T) dependence in the ab-plane.

Electron irradiation and annealing effects on the pseudogap in optimally doped YBCO single crystals

2020 ◽  
Vol 34 (14) ◽  
pp. 2050151
Author(s):  
G. Ya. Khadzhai ◽  
R. V. Vovk ◽  
S. F. Zdorovko ◽  
A. Chroneos
Keyword(s):  
Single Crystals ◽  
Mean Field Theory ◽  
Mean Field ◽  
Excess Conductivity ◽  
Fluctuation Conductivity ◽  
Fast Electrons ◽  
Exponential Temperature Dependence ◽  
Annealing Effects ◽  
The Mean ◽  
Field Transition

The effect of room-temperature annealing on the basal-plane conductivity of YBCO single crystals is investigated after their irradiation with fast electrons. It is revealed that the excess conductivity [Formula: see text] of the samples obeys an exponential temperature dependence in a broad temperature range [Formula: see text]. Here, [Formula: see text] is the crossover temperature from the pseudogap to the fluctuation conductivity regime. The description of the excess conductivity with the expression [Formula: see text] can be interpreted in terms of the mean-field theory where [Formula: see text] corresponds to the mean-field transition temperature to the pseudogap state and the dependence [Formula: see text] is described within the framework of the BCS-BEC crossover theory.

scholarly journals EVOLUTION OF OVER-CONDUCTIVITY OF YВа2Сu3О7-δ SINGLE CRYSTALS UNDER THE EXPOSURE OF IRRADIATION BY HIGH-ENERGY ELECTRONS

2020 ◽  
pp. 9-15
Author(s):  
N.A. Azarenkov ◽  
V.N. Voyevodin ◽  
R.V. Vovk ◽  
N.R. Vovk ◽  
G.Ya. Khadzhai ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Single Crystals ◽  
Electron Irradiation ◽  
Mean Field Theory ◽  
Mean Field ◽  
High Energy ◽  
Excess Conductivity ◽  
Crossover Point ◽  
Temperature Range ◽  
The Mean

The evolution of the excess conductivity of YВа2Сu3О7-δ single crystals upon electron irradiation is investigated. It was shown that electron irradiation leads to a significant expansion of the temperature range for the existence of excess conductivity, thereby narrowing the region of the linear dependence of ρ(Т) in the ab plane. It was found that the excess conductivity ∆σ(Т) of YВа2Сu3О7-δ single crystals in a wide temperature range Tf<Т<T* (Тf – the transition temperature from the PG to the FP mode) is subject to exponential temperature dependence. Moreover, the description of excess conductivity using the relation ∆σ ~ (1-Т/Т*)exp( ∆*ab/T) (Δ*ab – the pseudogap in ab-plane) can be interpreted in terms of the mean-field theory, where T* is presented as the mean-field temperature of the transition to the PG state, and the temperature dependence of the pseudogap is satisfactorily described in the framework of the BCS-BEC crossover theory. In this case, the value of the transverse coherence length ξс(0) increases 1.4 times and the 2D-3D crossover point shifts in temperature.

scholarly journals Evidence of exactness of the mean-field theory in the nonextensive regime of long-range classical spin models

2000 ◽  
Vol 61 (17) ◽  
pp. 11521-11528 ◽  
Author(s):  
Sergio A. Cannas ◽  
A. C. N. de Magalhães ◽  
Francisco A. Tamarit
Keyword(s):  
Field Theory ◽  
Long Range ◽  
Mean Field Theory ◽  
Mean Field ◽  
Spin Models ◽  
Classical Spin ◽  
The Mean ◽  
Classical Spin Models

Capillary waves and the mean field theory of interfaces

1977 ◽  
Vol 67 (8) ◽  
pp. 3636-3641 ◽  
Author(s):  
H. Ted Davis
Keyword(s):  
Field Theory ◽  
Mean Field Theory ◽  
Mean Field ◽  
Capillary Waves ◽  
The Mean
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