A DOMAIN MODEL OF CUPRATES

1994 ◽  
Vol 08 (22) ◽  
pp. 3083-3094 ◽  
Author(s):  
V. DALLACASA
Keyword(s):  
Fermi Liquid ◽  
Characteristic Length ◽  
Domain Model ◽  
Linear Temperature Dependence ◽  
Arbitrary Length ◽  
Linear Temperature ◽  
Bcs Model ◽  
Marginal Fermi Liquid ◽  
System Length ◽  
Enhanced Superconductivity

We have investigated the occurrence of superconductivity in a Fermi liquid of finite volume, under the assumption of a sharp surface, by solving numerically (at arbitrary length) and analytically (at the smallest lengths) the Cooper–BCS model. We find that this model can predict enhanced superconductivity with respect to the bulk BCS model when the system length L ≪ L0, in which L0 is a characteristic length. Under the same conditions the normal state is found to behave anomalously with respect to the conventional Fermi liquid, with a linear temperature dependence of the resistivity and marginal Fermi liquid properties. The results are used to implement a domain model of high T c superconductors.

scholarly journals Bad metallic transport in a cold atom Fermi-Hubbard system

Science ◽  
2018 ◽  
Vol 363 (6425) ◽  
pp. 379-382 ◽  
Author(s):  
Peter T. Brown ◽  
Debayan Mitra ◽  
Elmer Guardado-Sanchez ◽  
Reza Nourafkan ◽  
Alexis Reymbaut ◽  
...  
Keyword(s):  
Diffusion Constant ◽  
Cold Atom ◽  
Quantum Systems ◽  
Strong Interactions ◽  
Einstein Relation ◽  
Linear Temperature Dependence ◽  
Many Body ◽  
Linear Temperature ◽  
Density Modulation ◽  
Shed Light

Strong interactions in many-body quantum systems complicate the interpretation of charge transport in such materials. To shed light on this problem, we study transport in a clean quantum system: ultracold lithium-6 in a two-dimensional optical lattice, a testing ground for strong interaction physics in the Fermi-Hubbard model. We determine the diffusion constant by measuring the relaxation of an imposed density modulation and modeling its decay hydrodynamically. The diffusion constant is converted to a resistivity by using the Nernst-Einstein relation. That resistivity exhibits a linear temperature dependence and shows no evidence of saturation, two characteristic signatures of a bad metal. The techniques we developed in this study may be applied to measurements of other transport quantities, including the optical conductivity and thermopower.

scholarly journals Modelling the structural variation of quartz and germanium dioxide with temperature by means of transformed crystallographic data

2021 ◽  
Vol 77 (3) ◽  
Author(s):  
Maximilian Fricke ◽  
Noel W. Thomas
Keyword(s):  
Structure Prediction ◽  
Structural Variation ◽  
Germanium Dioxide ◽  
Reverse Transformation ◽  
Linear Temperature Dependence ◽  
Structural Analogue ◽  
Acta Cryst ◽  
Linear Temperature ◽  
First Order ◽  
Angle Parameter

The pseudocubic (PC) parameterization of O4 tetrahedra [Reifenberg & Thomas (2018). Acta Cryst. B74, 165–181] is applied to quartz (SiO2) and its structural analogue germanium dioxide (GeO2). In α-quartz and GeO2, the pseudocubes are defined by three length parameters, a PC, b PC and c PC, together with an angle parameter αPC. In β-quartz, αPC has a fixed value of 90°. For quartz, the temperature evolution of parameters for the pseudocubes and the silicon ion network is established by reference to the structural refinements of Antao [Acta Cryst. (2016), B72, 249–262]. In α-quartz, the curve-fitting employed to express the non-linear temperature dependence of pseudocubic length and Si parameters exploits the model of a first-order Landau phase transition utilized by Grimm & Dorner [J. Phys. Chem. Solids (1975), 36, 407–413]. Since values of tetrahedral tilt angles about 〈100〉 axes also result from the pseudocubic transformation, a curve for the observed non-monotonic variation of αPC with temperature can also be fitted. Reverse transformation of curve-derived values of [Si+PC] parameters to crystallographic parameters a, c, x Si, x O, y O and z O at interpolated or extrapolated temperatures is demonstrated for α-quartz. A reverse transformation to crystallographic parameters a, c, x O is likewise carried out for β-quartz. This capability corresponds to a method of structure prediction. Support for the applicability of the approach to GeO2 is provided by analysing the structural refinements of Haines et al. [J. Solid State Chem. (2002), 166, 434–441]. An analysis of trends in tetrahedral distortion and tilt angle in α-quartz and GeO2 supports the view that GeO2 is a good model for quartz at high pressure.

scholarly journals Transport Anomalies and Marginal-Fermi-Liquid Effects at a Quantum Critical Point

2000 ◽  
Vol 85 (21) ◽  
pp. 4602-4605 ◽  
Author(s):  
D. Belitz ◽  
T. R. Kirkpatrick ◽  
R. Narayanan ◽  
Thomas Vojta
Keyword(s):  
Critical Point ◽  
Fermi Liquid ◽  
Quantum Critical Point ◽  
Marginal Fermi Liquid ◽  
Quantum Critical

ELECTRONIC PAIRING AND VARIATION IN THE NORMAL STATE OF METAL

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3467-3471
Author(s):  
LIYUAN ZHANG ◽  
QIANG HAN
Keyword(s):  
Normal State ◽  
Fermi Liquid ◽  
Experimental Studies ◽  
Two Dimension ◽  
Marginal Fermi Liquid

Reviewing the situation of the experimental studies of the normal state in high-Tc super-conductors (HTS), we have put forward nine points to be necessarily considered in any theory of the normal state in HTS. It is argued that the two-dimension two-subsystem model is at least qualitatively consistent with all these nine points. On the basis of these arguments, the problem of the electronic pairing and variation in the normal state of metal has been discussed. We have put forward three variation of metals, i.e. the conventional metal (Fermi liquid), near conventional metal and the metal with the markedly pseudogapped metallic behaviour which may be a marginal Fermi liquid.

Processing Path and The Evolution of Crystallinity in Rapidly Solidified Glassy Alloys

1994 ◽  
Vol 362 ◽  
Author(s):  
M. A. Otooni
Keyword(s):  
Transition Temperature ◽  
Thermomechanical Properties ◽  
Relaxation Processes ◽  
Linear Temperature Dependence ◽  
Linear Temperature ◽  
Glassy Alloys ◽  
Atomic Transport ◽  
The Subject ◽  
Rapidly Solidified ◽  
Selection Of

AbstractAtomic transport properties in rapidly solidified glassy alloys are not fully understood in spite of much experimental data on the subject. Nevertheless, a thorough understanding of these properties is of fundamental importance when studying the practical limits of the application of rapidly solidified glassy alloys.Several attempts are made in this paper to explain our experimental results on the mechanical flow properties near the transition temperature, Tr. These results are interpreted in the context of possible operating mechanisms such as diffusion and/or relaxation processes. Some inferences have been made on the nature of viscosity and its fluctuation near the transition temperature. The linear temperature dependence of the viscosity near the transition temperature is explained by invoking the free-volume concept for the viscosity of the glassy alloys.These results are used to provide appropriate data for the selection of feasible processing paths which will produce alloys with advanced thermomechanical properties.

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