METAL–INSULATOR TRANSITION AND THE TEMPERATURE OF THE PSEUDOGAP ANOMALY OPENING IN PRASEODYMIUM DOPED Y1-zPrzBa2Cu3O7-δ SINGLE CRYSTALS

2013 ◽  
Vol 27 (04) ◽  
pp. 1350029 ◽  
Author(s):  
R. V. VOVK ◽  
Z. F. NAZYROV ◽  
I. L. GOULATIS ◽  
A. CHRONEOS ◽  
V. M. PINTO SIMOES
Keyword(s):  
Electrical Resistivity ◽  
Single Crystals ◽  
Insulator Transition ◽  
Critical Regime ◽  
Significant Shift ◽  
Asymptotic Dependence ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
The One ◽  
Praseodymium Doping

The influence of praseodymium doping on the electrical resistivity in the ab-plane of Y 1-z Pr z Ba 2 Cu 3 O 7-δ single crystals, is investigated. It is determined that as the concentration of praseodymium (0.0 ≤ z ≤ 0.5) is rising there occurs a significant shift of the temperature regions, corresponding to the metal–insulator transitions, as well as to the regime of the implementation of the pseudogap anomaly. The part of the curves related to the metal–insulator transition are well described by means of an asymptotic dependence that corresponds to the implementation of a quantum critical regime in the system, the so-called law of the "one third".

COEXISTENCE OF DIFFERENT TYPES OF TRANSVERSE CONDUCTIVITY IN Y1-xPrxBa2Cu3 O7-δ SINGLE CRYSTALS WITH DIFFERENT PRASEODYMIUM CONCENTRATIONS

2013 ◽  
Vol 27 (27) ◽  
pp. 1350198 ◽  
Author(s):  
R. V. VOVK ◽  
N. R. VOVK ◽  
I. L. GOULATIS ◽  
A. CHRONEOS
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Single Crystals ◽  
Insulator Transition ◽  
Superconducting Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Different Types ◽  
Transverse Conductivity ◽  
Praseodymium Doping

In this paper, the influence of praseodymium doping on the conductivity across (transverse) the basal plane of high-temperature superconducting Y 1-x Pr x Ba 2 Cu 3 O 7-δ single crystals is investigated. It is determined that an increase of praseodymium doping leads to increased localization effects and the implementation of a metal–insulator transition Y 1-x Pr x Ba 2 Cu 3 O 7-δ, which always precedes the superconducting transition. The increase of the praseodymium concentration also leads to a significant displacement of the point of the metal–insulator transition to the low temperature region.

THE EFFECT OF HYDROSTATIC PRESSURE ON METAL–INSULATOR TRANSITION IN QUANTUM WELL SEMICONDUCTOR SYSTEMS II

2005 ◽  
Vol 04 (01) ◽  
pp. 45-53 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Hydrostatic Pressure ◽  
Quantum Well ◽  
Ionization Energy ◽  
Critical Concentration ◽  
Shallow Donor ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Mass Approximation ◽  
The One

Using a variational procedure within the effective mass approximation, the ionization energies of a shallow donor in a quantum well (QW) of GaAs/Ga 1-x Al x As superlattice system under the influence of pressure with the exact dielectric function are obtained. The vanishing of ionization energy initiating Mott transition is observed within the one-electron approximation. The effects of Anderson localization using a simple model, and exchange and correlation in the Hubbard model are included in this model. It is found that the ionization energy (i) increases when well width increases for a given pressure, (ii) decreases and reaches a bulk value for a larger well width, (iii) increases with increasing external hydrostatic pressure for a given QW thickness, and (iv) the critical concentration at which the metal–insulator transition (MIT) occurs is increased when pressure is applied. It also is demonstrated that MIT is not possible in a hydrostatic pressure in a quantum well supporting scaling theory of localization. All the calculations have been carried out with finite and infinite barriers and the results are compared with available data in the literature.

Effect of uniaxial pressure on metal-insulator transition in (Sm1−yNdy)0.52Sr0.48MnO3 single crystals

2009 ◽  
Vol 94 (25) ◽  
pp. 252506 ◽  
Author(s):  
A. Murugeswari ◽  
P. Sarkar ◽  
S. Arumugam ◽  
N. Manivannan ◽  
P. Mandal ◽  
...  
Keyword(s):  
Single Crystals ◽  
Insulator Transition ◽  
Uniaxial Pressure ◽  
Metal Insulator Transition ◽  
Metal Insulator
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