scholarly journals Unusual metallic conductivity of high-Tc cuprates

2021 ◽  
Vol 5 (3) ◽  
pp. 183-191
Author(s):  
S. Dzhumanov ◽  
Sh.R. Malikov ◽  
Sh.S. Djumanov
Keyword(s):  
Transport Theory ◽  
Charge Carriers ◽  
Cooper Pairs ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
High Tc ◽  
Distinctive Features ◽  
Metallic Conductivity ◽  
Temperature Dependences ◽  
High Tc Cuprates

The intrinsic mechanisms of the unusual metallic transports of three types of relevant charge carriers (large polarons, excited (dissociated) polaronic components of bosonic Cooper pairs and bosonic Cooper pairs themselves) along the CuO2 layers of high-Tc cuprates are identified and the new features of metallic conductivity in the CuO2 layers (i.e. ab -planes) of underdoped and optimally doped cuprates are explained. The in-plane conductivity of high-Tc cuprates is associated with the metallic transports of such charge carriers at their scattering by lattice vibrations in thin CuO2 layers. The proposed charge transport theory in high-Tc cuprates allows to explain consistently the distinctive features of metallic conductivity and the puzzling experimental data on the temperature dependences of their in-plane resistivity pab. In underdoped and optimally doped cuprates the linear temperature dependence of pab(T) above the pseudogap formation temperature T∗ is associated with the scattering of polaronic carriers at acoustic and optical phonons, while the different (upward and downward) deviations from the linearity in pab(T) below T∗ are caused by the pseudogap effect on the conductivity of the excited Fermi components of bosonic Cooper pairs and by the dominating conductivity of bosonic Cooper pairs themselves in the normal state of these high-Tc materials.

ANOMALOUS SPIN DENSITY WAVE SUPERCONDUCTIVITY IN CUPRATE HIGH-Tc SUPERCONDUCTORS

2009 ◽  
Vol 23 (12) ◽  
pp. 1533-1538
Author(s):  
JE HUAN KOO ◽  
JUNG-HYUN KIM ◽  
JONG-MUN JEONG ◽  
GUANGSUP CHO ◽  
JONG-JEAN KIM
Keyword(s):  
Spin Density ◽  
Density Wave ◽  
Spin Density Wave ◽  
Charge Density Waves ◽  
Electron Interaction ◽  
Cooper Pairs ◽  
Linear Temperature Dependence ◽  
Density Waves ◽  
Linear Temperature ◽  
High Tc

Spin density waves (SDWs) may be thought of as comprising charge density waves (CDWs) in pairs, with one CDW composed of up-spin electrons and the other composed of down-spin electrons. The superconductivity in cuprates may then be said to be caused by the BCS-type pairing of these SDWs. This is no longer a simple Cooper pairing of singlet electrons but one that involves a collection of Cooper pairs. Transport in normal metallic states is then governed by CDW pinning, as in a quantum well that is characterized by linear temperature dependence. The pseudo-gap may be understood as originating from this BCS-type gap with SDW, where the parameters used are from those of the original BCS scheme except that the electron–electron interaction is multiplied by N CDW , which is the number of electrons that have the same spin direction belonging to one CDW branch of the pair that comprises the SDW.

MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS X—ESR OF Gd IN Y-Ba-Cu-O BETWEEN ABOUT Tcand 600°C

1992 ◽  
Vol 06 (24) ◽  
pp. 1525-1530 ◽  
Author(s):  
K. SUGAWARA ◽  
S. TANAKA
Keyword(s):  
Temperature Gradient ◽  
Temperature Dependence ◽  
Inhomogeneous Magnetic Field ◽  
Linear Temperature Dependence ◽  
High Temperature Side ◽  
Linear Temperature ◽  
High Tc ◽  
Absorption Studies ◽  
Zero Resistance ◽  
Temperature Side

Temperature dependence of ESR linewidth, ΔHPP, of Gd3+ in Y1−xGdxBa2Cu3Oy (x=0.2, 0.5 and 1) has been studied between about Tc (zero-resistance temperature) and about 600°C. For all the samples, ΔHPP progressively broadens as temperature approaches Tc from high temperature side, presumably due to inhomogeneous magnetic field distributions arising from superconductivity. On the contrary, ΔHpp is nearly linear in temperature between about 100 K and 600 K with temperature gradient, ∂(ΔHPP)/∂T~0.6 G/deg. The linear temperature dependence is assumed to be due to the Korringa relation. From the temperature gradient obtained above, JN(EF) was estimated as 0.0025, where J is the coupling coefficient between Gd spin S and conduction carrier’s spin S, and N(EF) is the density of states on the Fermi surface. In addition, by substituting an appropriate value for J, N(EF) was crudely estimated for the Y-Gd-Ba-Cu-O system.

PHONON DRAG, CARRIER DIFFUSIVE THERMOELECTRIC POWER AND SEMICONDUCTING RESISTIVITY BEHAVIOR OF Zn NANOWIRES

2010 ◽  
Vol 09 (05) ◽  
pp. 453-459
Author(s):  
K. K. CHOUDHARY ◽  
D. PRASAD ◽  
K. JAYAKUMAR ◽  
DINESH VARSHNEY
Keyword(s):  
Grain Boundaries ◽  
Thermoelectric Power ◽  
Charge Carriers ◽  
Fourth Power ◽  
Linear Temperature Dependence ◽  
Phonon Drag ◽  
Acoustic Phonons ◽  
Temperature Dependent ◽  
Linear Temperature ◽  
Model Hamiltonian

In this paper, we undertake a quantitative analysis of observed temperature-dependent thermoelectric power (S) of 4 nm Zn /Vycor composite nanowires by developing a model Hamiltonian that incorporates scattering of acoustic phonons with impurities, grain boundaries, charge carriers and phonons. Mott expression is used to determine the carrier diffusive thermoelectric power [Formula: see text]. The [Formula: see text] shows linear temperature dependence and the computed [Formula: see text] when subtracted from the experimental data is interpreted as phonon drag thermoelectric power [Formula: see text]. The model Hamiltonian within the relaxation time approximation sets the limitations of the scattering of acoustic phonons with impurities, grain boundaries, charge carriers and phonons for thermoelectric power in the nanowires. It is shown that for acoustic phonons the scattering and transport cross sections are proportional to fourth power of the phonon in the Rayleigh regime. The resultant thermoelectric powers is an artefact of various operating scattering mechanisms and are computed for the first time to our knowledge for Zn nanowires consistent with the experimentally reported behavior. The semiconducting nature of resistivity is discussed with small polaron conduction (SPC) model which consistently retraces the temperature-dependent resistivity behavior of Zn /Vycor composite.

scholarly journals Fractional Statistics of Charge Carriers in the One- and Two-Dimensional t-J Model: A Hint for the Cuprates?

2020 ◽  
Vol 5 (1) ◽  
pp. 12
Author(s):  
Pieralberto Marchetti
Keyword(s):  
Exact Solution ◽  
Charge Carriers ◽  
One Dimension ◽  
Two Dimensional ◽  
High Tc ◽  
One Dimensional ◽  
Similarities And Differences ◽  
Composite Nature ◽  
The One ◽  
High Tc Cuprates

We show that we can interpret the exact solution of the one-dimensional t-J model in the limit of small J in terms of charge carriers with both exchange (braid) and exclusion (Haldane) statistics with parameter 1/2. We discuss an implementation of the same statistics in the two-dimensional t-J model, emphasizing similarities and differences with respect to one dimension. In both cases, the exclusion statistics is a consequence of the no-double occupation constraint. We argue that the application of this formalism to hole-doped high Tc cuprates and the derived composite nature of the hole give a hint to grasp many unusual properties of these materials.

CHANGES IN THE SUPERCONDUCTING PROPERTIES OF HIGH-Tc CUPRATES PRODUCED BY APPLIED ELECTRIC FIELDS

1992 ◽  
Vol 06 (10) ◽  
pp. 555-571 ◽  
Author(s):  
J. MANNHART
Keyword(s):  
Transport Properties ◽  
Electric Fields ◽  
Superconducting State ◽  
Experimental Studies ◽  
Charge Carriers ◽  
Superconducting Properties ◽  
Mobile Charge ◽  
High Tc ◽  
High Tc Cuprates

By changing the concentration of mobile charge carriers, applied electric fields influence the transport properties of high-T c superconductors in the superconducting state. Experimental studies of these effects are briefly reviewed.

DISTINCTIVE FEATURES OF NOVEL SUPERCONDUCTING TRANSITIONS IN UNDERDOPED AND OVERDOPED HIGH-Tc CUPRATES

2005 ◽  
Vol 19 (01n03) ◽  
pp. 43-45
Author(s):  
S. DZHUMANOV ◽  
J. D. FAN
Keyword(s):  
Phase Transitions ◽  
Liquid State ◽  
Cooper Pair ◽  
Pair Formation ◽  
High Tc ◽  
Distinctive Features ◽  
Bose Liquid ◽  
Pair Condensation ◽  
High Tc Cuprates ◽  
Superconducting Transitions

It is argued that the new theory that combines the precursor BCS-like non-superconducting (SC) pairing and the Cooper-pair condensation into a superfluid Bose-liquid state is more plausible than the standard SC fluctuation approach in describing the distinctive features of the underdoped and overdoped high-Tc cuprates. We show that the scenarios for high-Tc superconductivity in these materials are quite different on the character of the Cooper-pair formation and SC phase transitions.

DYNAMICS OF TWIN BOUNDARIES AND HIGH Tc SUPERCONDUCTORS

1987 ◽  
Vol 01 (03n04) ◽  
pp. 931-940
Author(s):  
B. Horovitz ◽  
G.R. Barsch ◽  
J.A. Krumhansl
Keyword(s):  
Specific Heat ◽  
Temperature Dependence ◽  
Electronic Properties ◽  
Twin Boundary ◽  
Linear Temperature Dependence ◽  
High Tc Superconductors ◽  
Linear Temperature ◽  
High Tc ◽  
Vertex Corrections ◽  
Anisotropic Dispersion

The formation of coherent arrays of twins in a tetragonal to orthorhombic transition and its effects on electronic properties are studied. The twin boundary oscillations (“dyadons”) have an anisotropic dispersion with frequencies typically ≲1010 sec −1 for wavevectors perpendicular to the boundaries. This results in a ~T2 contribution to the specific heat for T≳ 1° K and a linear temperature dependence of the resistivity. The unusual anisotropy yields vertex corrections which diverge at high temperatures and can enhance T c.

THERMOPOWER AND ELECTRICAL RESISTIVITY OF LaxY1−xAl2 ALLOYS

1993 ◽  
Vol 07 (01n03) ◽  
pp. 387-390
Author(s):  
A. T. BURKOV ◽  
E. BAUER ◽  
E. GRATZ ◽  
R. RESEL
Keyword(s):  
Electrical Resistivity ◽  
Fermi Level ◽  
Elevated Temperatures ◽  
Transport Theory ◽  
Minor Effect ◽  
Boltzmann Transport ◽  
Linear Temperature ◽  
Temperature Dependences ◽  
A Minor ◽  
D Model

The electronic transport theory predicts linear temperature dependences for the thermopower (S) and the electrical resistivity (ρ) at elevated temperatures. However, the experimental data for La x Y 1− x Al 2 alloys reveal nonlinear dependences for both, S(T) and ρ (T) . We relate this disagreement to the density of states (DOS) structure in the vicinity of the Fermi level. Based on the linearised Boltzmann transport equation, we obtain from the experimental temperature dependences of ρ and S an electron dependent function ϕ(ε), reflecting the energy dependence of DOS and that of scattering processes. In the scope of Mott's s-d model the 1/ϕ(ε) function is proportional to the DOS near the Fermi level. A comparison of the 1/ϕ(ε) function with available band structure calculations shows good agreement for YAl 2 and LaAl 2. In the case of alloys, the structure of DOS may cause a temperature dependence of the impurity contribution to the resistivity but has only a minor effect on S(T) at evelated temperatures.

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