scholarly journals Disorder-Induced Superconductor-Insulator Transition

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Zeleke Deressa ◽  
P. Singh
Keyword(s):  
Condensed Matter ◽  
Critical Value ◽  
Cooper Pairs ◽  
2D Systems ◽  
Electric Resistance ◽  
Superconducting Properties ◽  
Direct Transition ◽  
2D System ◽  
Infinite Conductivity ◽  
Opposite Extreme

In this paper, we report the results of our theoretical investigation on the interplay of superconductivity and disorder in two-dimensional (2D) systems. The effect of disorder on superconductivity of 2D systems was found analytically using Green’s function formalism. The results of our calculation revealed that disorder induced due to randomly distributed superconducting islands enhances decoherence of Cooper pairs and suppresses superconductivity. We have also determined the critical value of disorder at which the 2D system completely loses its superconducting properties. Below this critical value of disorder, the system acts as a superconductor, a system with zero electrical resistance. Above the critical value, it acts as an insulator, a system with infinite electric resistance. This is a fascinating result because a direct transition from the state of the infinite conductivity to the opposite extreme of infinite resistivity is unexpected in the theory of condensed matter physics.

scholarly journals Strain-stabilized superconductivity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J. P. Ruf ◽  
H. Paik ◽  
N. J. Schreiber ◽  
H. P. Nair ◽  
L. Miao ◽  
...  
Keyword(s):  
Thin Films ◽  
Materials Science ◽  
Condensed Matter ◽  
Quantum States ◽  
Low Energy ◽  
Superconducting Transition ◽  
Superconducting Properties ◽  
Detailed Understanding ◽  
Epitaxial Strain ◽  
Promising Strategy

AbstractSuperconductivity is among the most fascinating and well-studied quantum states of matter. Despite over 100 years of research, a detailed understanding of how features of the normal-state electronic structure determine superconducting properties has remained elusive. For instance, the ability to deterministically enhance the superconducting transition temperature by design, rather than by serendipity, has been a long sought-after goal in condensed matter physics and materials science, but achieving this objective may require new tools, techniques and approaches. Here, we report the transmutation of a normal metal into a superconductor through the application of epitaxial strain. We demonstrate that synthesizing RuO2 thin films on (110)-oriented TiO2 substrates enhances the density of states near the Fermi level, which stabilizes superconductivity under strain, and suggests that a promising strategy to create new transition-metal superconductors is to apply judiciously chosen anisotropic strains that redistribute carriers within the low-energy manifold of d orbitals.

scholarly journals Superconducting properties and pseudogap from preformed Cooper pairs in the triclinic(CaFe1−xPtxAs)10Pt3As8

2015 ◽  
Vol 91 (10) ◽  
Author(s):  
M. A. Surmach ◽  
F. Brückner ◽  
S. Kamusella ◽  
R. Sarkar ◽  
P. Y. Portnichenko ◽  
...  
Keyword(s):  
Cooper Pairs ◽  
Superconducting Properties

scholarly journals Critical fermion density for restoring spontaneously broken symmetry

2015 ◽  
Vol 30 (24) ◽  
pp. 1550122
Author(s):  
Hagen Kleinert ◽  
She-Sheng Xue
Keyword(s):  
Particle Physics ◽  
Nuclear Physics ◽  
Condensed Matter ◽  
Critical Value ◽  
Broken Symmetry ◽  
Physical Systems ◽  
Symmetry Breakdown ◽  
The Standard Model ◽  
Text Model ◽  
Spontaneous Symmetry Breakdown

We show how the phenomenon of spontaneous symmetry breakdown is affected by the presence of a sea of fermions in the system. When its density exceeds a critical value, the broken symmetry can be restored. We calculate the critical value and discuss the consequences for three different physical systems: First, for the Standard Model (SM) of particle physics, where the spontaneous symmetry breakdown leads to nonzero masses of intermediate gauge bosons and fermions. The symmetry restoration will greatly enhance various processes with dramatic consequences for the early universe. Second, for the Gell-Mann–Lévy [Formula: see text]-model of nuclear physics, where the symmetry breakdown gives rise to the nucleon and meson masses. The symmetry restoration may have important consequences for formation or collapse of stellar cores. Third, for the superconductive phase of condensed-matter, where the BCS condensate at low-temperature may be destroyed by a too large electron density.

On the Liquid-Flow Analog To Evaluate Gas Wells Producing in Shales

2013 ◽  
Vol 16 (02) ◽  
pp. 209-215 ◽  
Author(s):  
C.. Chen ◽  
R.. Raghavan
Keyword(s):  
Liquid Flow ◽  
Horizontal Well ◽  
Numerical Solutions ◽  
Transient Flow ◽  
Constant Pressure ◽  
Hydraulic Fractures ◽  
2D System ◽  
Infinite Conductivity ◽  
Linear Reservoir ◽  
Fractured Well

Summary Drawing on links to the analog considered by Al-Hussainy et al. (1966), we present a corresponding analog to correlate solutions for a fractured well producing at a constant pressure. A solution in terms of the similarity transformation for the pressure distribution in a linear reservoir filled with a real gas provides the basis. This solution is particularly suited to demonstrate that anomalous results will be obtained when long linear-flow trends typical of shales produced through a horizontal well consisting of multiple, infinite-conductivity fractures are evaluated in classical terms. The basis for the liquid-flow analog is re-examined by considering 2D numerical solutions for a fractured well producing a gas reservoir at a constant pressure. A method to correlate the nonlinear solutions with the corresponding liquid-flow solutions for fractured wells producing at a constant pressure during the infinite-acting period is provided. The phrase “analog” used here represents attempts to match values of both the well response and its derivative for a 2D system during transient flow. This correlation enables analysts to obtain estimates that are accurate in the manner of Al-Hussainy et al. (1966). An example illustrates the application of this recommendation for a horizontal well producing a shale reservoir through multiple hydraulic fractures.

A POSSIBLE NEW TYPE OF SUPERCONDUCTIVITY

1996 ◽  
Vol 10 (03n05) ◽  
pp. 173-179
Author(s):  
M.P. DAS ◽  
L.J. TASSIE
Keyword(s):  
Cosmic Strings ◽  
Condensed Matter ◽  
Condensed Matter Physics ◽  
Superconducting Properties ◽  
New Type

It is suggested that the mechanism for superconductivity proposed by Witten for cosmic strings can also occur in the laboratory. Each term in Witten’s Lagrangian has an analogue in the theory of condensed matter physics. The parameters in condensed matter are many orders of magnitude different from those in cosmic strings. Some estimates of the possible superconducting properties are given.

scholarly journals Resonating valence bonds and spinon pairing in the Dicke model

2018 ◽  
Vol 4 (6) ◽  
Author(s):  
R. Ganesh ◽  
L. Theerthagiri ◽  
G. Baskaran
Keyword(s):  
Ground State ◽  
Cavity Qed ◽  
Condensed Matter ◽  
Photon Emission ◽  
Valence Bond ◽  
Cooper Pairs ◽  
Many Body ◽  
Initial State ◽  
Continuous Transition ◽  
Dark State

Resonating valence bond (RVB) states are a class of entangled quantum many body wavefunctions with great significance in condensed matter physics. We propose a scheme to synthesize a family of RVB states using a cavity QED setup with two-level atoms coupled to a common photon mode. In the lossy cavity limit, starting with an initial state with MM atoms excited and NN atoms in the ground state, we show that this setup can be configured as a Stern Gerlach experiment. A measurement of photon emission collapses the wavefunction of atoms onto an RVB state composed of resonating long-ranged singlets. Each emitted photon reduces the number of singlets by unity, replacing it with a pair of lone spins or ‘spinons’. As spinons are formed coherently in pairs, they are analogous to Cooper pairs in a superconductor. To simulate pair fluctuations, we propose a protocol in which photons are allowed to escape the cavity undetected. This leads to an inchoate superconductor – mixed quantum state with a fluctuating number of spinon pairs. Remarkably, in the limit of large system sizes, this protocol reveals an underlying quantum phase transition. Upon tuning the initial spin polarization, the emission exhibits a continuous transition from a dark state to a bright state. This opens an exciting route to simulate RVB states and superconductivity.

scholarly journals Stability andl1-Gain Analysis for Positive 2D Systems with State Delays in the Roesser Model

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Zhaoxia Duan ◽  
Hamid Reza Karimi ◽  
Zhengrong Xiang
Keyword(s):  
Sufficient Conditions ◽  
Linear Matrix ◽  
2D Systems ◽  
Matrix Inequalities ◽  
Roesser Model ◽  
State Delays ◽  
Lyapunov Function Method ◽  
2D System ◽  
Delay Dependent ◽  
Delay Dependent Stability

This paper considers the problem of delay-dependent stability andl1-gain analysis for positive 2D systems with state delays described by the Roesser model. Firstly, the copositive-type Lyapunov function method is used to establish the sufficient conditions for the addressed positive 2D system to be asymptotically stable. Then,l1-gain performance for the system is also analyzed. All the obtained results are formulated in the form of linear matrix inequalities (LMIs) which are computationally tractable. Finally, an illustrative example is given to verify the effectiveness of the proposed results.

scholarly journals PHASE FLUCTUATIONS AND NON-FERMI LIQUID PROPERTIES OF 2D FERMI-SYSTEM WITH ATTRACTION

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3510-3512 ◽  
Author(s):  
VALERY P. GUSYNIN ◽  
VADIM M. LOKTEV ◽  
RACHEL M. QUICK ◽  
SERGEI G. SHARAPOV
Keyword(s):  
Green Function ◽  
Spectral Density ◽  
Fermi Liquid ◽  
Fermi System ◽  
Superconducting Properties ◽  
Phase Fluctuations ◽  
Liquid Behavior ◽  
Analytic Expressions ◽  
2D System ◽  
Dynamical Fluctuations

The effect of static fluctuations in the phase of the order parameter on the normal and superconducting properties of a 2D system with attractive four-fermion interaction has been studied. Analytic expressions for the fermion Green function, its spectral density and the density of states are derived. The resultant single-particle Green function clearly demonstrates non-Fermi liquid behavior. The results show that as the temperature increases through the 2D critical temperature the width of the quasiparticle peaks broadens significantly. At the same time one retains the gap in quasiparticle spectrum. The spectral density for the dynamical fluctuations can also be obtained. Clearly the dynamical fluctuations fill the gap giving the observed pseudogap behaviour.

Characterization of Y-Ba-Cu-O films grown on silicon substrates by sequential evaporation

1988 ◽  
Vol 46 ◽  
pp. 866-867
Author(s):  
E. L. Hall ◽  
A. Mogro-Campero ◽  
L. G. Turner ◽  
N. Lewis
Keyword(s):  
Thin Film ◽  
Thin Film Deposition ◽  
Superconducting Films ◽  
Electron Beam Evaporation ◽  
Film Deposition ◽  
Silicon Substrates ◽  
Superconducting Properties ◽  
Sequential Electron ◽  
Thin Superconducting Films

There is great interest in the growth of thin superconducting films of YBa2Cu3Ox on silicon, since this is a necessary first step in the use of this superconductor in a variety of possible electronic applications including interconnects and hybrid semiconductor/superconductor devices. However, initial experiments in this area showed that drastic interdiffusion of Si into the superconductor occurred during annealing if the Y-Ba-Cu-O was deposited direcdy on Si or SiO2, and this interdiffusion destroyed the superconducting properties. This paper describes the results of the use of a zirconia buffer layer as a diffusion barrier in the growth of thin YBa2Cu3Ox films on Si. A more complete description of the growth and characterization of these films will be published elsewhere.Thin film deposition was carried out by sequential electron beam evaporation in vacuum onto clean or oxidized single crystal Si wafers. The first layer evaporated was 0.4 μm of zirconia.

Inelastic scattering at surfaces and interfaces

1986 ◽  
Vol 44 ◽  
pp. 392-393
Author(s):  
R. H. Ritchie ◽  
A. Howie
Keyword(s):  
Inelastic Scattering ◽  
Surface Properties ◽  
Correlation Energy ◽  
Condensed Matter ◽  
Charged Particles ◽  
Condensed Matter Physics ◽  
Optical Phonons ◽  
Exchange Correlation ◽  
Surfaces And Interfaces ◽  
Inelastic Interactions

An important part of condensed matter physics in recent years has involved detailed study of inelastic interactions between swift electrons and condensed matter surfaces. Here we will review some aspects of such interactions.Surface excitations have long been recognized as dominant in determining the exchange-correlation energy of charged particles outside the surface. Properties of surface and bulk polaritons, plasmons and optical phonons in plane-bounded and spherical systems will be discussed from the viewpoint of semiclassical and quantal dielectric theory. Plasmons at interfaces between dissimilar dielectrics and in superlattice configurations will also be considered.

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