scholarly journals Ginzburg-Landau effective action for a fluctuating holographic superconductor

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Yanyan Bu ◽  
Mitsutoshi Fujita ◽  
Shu Lin
Keyword(s):  
Effective Action ◽  
Order Parameter ◽  
Analytical Approach ◽  
Time Derivative ◽  
Time Dependent ◽  
Equilibrium System ◽  
Holographic Superconductor ◽  
Fluctuation Effect ◽  
Ginzburg Landau ◽  
First Order

Abstract Under holographic prescription for Schwinger-Keldysh closed time contour for non-equilibrium system, we consider fluctuation effect of the order parameter in a holographic superconductor model. Near the critical point, we derive the time-dependent Ginzburg-Landau effective action governing dynamics of the fluctuating order parameter. In a semi-analytical approach, the time-dependent Ginzburg-Landau action is computed up to quartic order of the fluctuating order parameter, and first order in time derivative.

scholarly journals Nonstationary Superconductivity: Quantum Dissipation and Time-Dependent Ginzburg-Landau Equation

2011 ◽  
Vol 2011 ◽  
pp. 1-10
Author(s):  
Anatoly A. Barybin
Keyword(s):  
Order Parameter ◽  
Continuity Equation ◽  
Chemical Potential ◽  
Landau Equation ◽  
Time Dependent ◽  
Quantum Dissipation ◽  
Ginzburg Landau ◽  
Superfluid Component ◽  
Ginzburg Landau Equation ◽  
Conservation Property

Transport equations of the macroscopic superfluid dynamics are revised on the basis of a combination of the conventional (stationary) Ginzburg-Landau equation and Schrödinger's equation for the macroscopic wave function (often called the order parameter) by using the well-known Madelung-Feynman approach to representation of the quantum-mechanical equations in hydrodynamic form. Such an approach has given (a) three different contributions to the resulting chemical potential for the superfluid component, (b) a general hydrodynamic equation of superfluid motion, (c) the continuity equation for superfluid flow with a relaxation term involving the phenomenological parameters and , (d) a new version of the time-dependent Ginzburg-Landau equation for the modulus of the order parameter which takes into account dissipation effects and reflects the charge conservation property for the superfluid component. The conventional Ginzburg-Landau equation also follows from our continuity equation as a particular case of stationarity. All the results obtained are mutually consistent within the scope of the chosen phenomenological description and, being model-neutral, applicable to both the low- and high- superconductors.

s-Wave holographic superconductor in different ensembles and its thermodynamic consistency

2017 ◽  
Vol 26 (04) ◽  
pp. 1750027
Author(s):  
Lei Yin ◽  
Defu Hou
Keyword(s):  
Order Parameter ◽  
Helmholtz Free Energy ◽  
Canonical Ensemble ◽  
Landau Theory ◽  
Equation Of Motion ◽  
Superconducting Phase ◽  
S Wave ◽  
Holographic Superconductor ◽  
Thermodynamic Relation ◽  
Ginzburg Landau

In this paper, we analytically study the consistency between the Ginzburg–Landau theory of the holographic superconductor in different ensembles and the fundamental thermodynamic relation, we derive the equation of motion of the scalar field which depicts the superconducting phase in canonical ensemble (CE) and a consistent formula to connect the holographic order-parameter to the Ginzburg–Landau coefficients in different thermodynamic ensembles, and we also study the spatially nonuniform Helmholtz free energy.

scholarly journals Multi-mode excitation drives disorder during the ultrafast melting of a C4-symmetry-broken phase

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Daniel Perez-Salinas ◽  
Allan S. Johnson ◽  
Dharmalingam Prabhakaran ◽  
Simon Wall
Keyword(s):  
Phase Transitions ◽  
Order Parameter ◽  
Landau Theory ◽  
Mean Field ◽  
Atomic Scale ◽  
Time Dependent ◽  
Ginzburg Landau ◽  
Mode Excitation ◽  
The Mean ◽  
Multi Mode

AbstractSpontaneous C4-symmetry breaking phases are ubiquitous in layered quantum materials, and often compete with other phases such as superconductivity. Preferential suppression of the symmetry broken phases by light has been used to explain non-equilibrium light induced superconductivity, metallicity, and the creation of metastable states. Key to understanding how these phases emerge is understanding how C4 symmetry is restored. A leading approach is based on time-dependent Ginzburg-Landau theory, which explains the coherence response seen in many systems. However, we show that, for the case of the single layered manganite La0.5Sr1.5MnO4, the theory fails. Instead, we find an ultrafast inhomogeneous disordering transition in which the mean-field order parameter no longer reflects the atomic-scale state of the system. Our results suggest that disorder may be common to light-induced phase transitions, and methods beyond the mean-field are necessary for understanding and manipulating photoinduced phases.

scholarly journals Attempt to Describe Phase Slips by Means of an Adiabatic Approximation

2021 ◽  
Author(s):  
Jorge Berger
Keyword(s):  
Superconducting State ◽  
Adiabatic Approximation ◽  
Landau Equation ◽  
Time Derivative ◽  
Time Dependent ◽  
Critical Voltage ◽  
Ginzburg Landau ◽  
Phase Drift ◽  
Derivative Term ◽  
Phase Slips

Abstract As a plausibility test for the feasibility of extension of the quasiclassical Keldysh–Usadel technique to slowly varying situations, we assess the influence of the time-derivative term in the time-dependent Ginzburg–Landau equation. We consider cases in which the superconducting state in a nanowire varies slowly, either because the voltage applied on it is small, or because most of phase drift takes place next to the boundaries. An approximation without this time derivative can describe the superconducting state away from phase slips, but is unable to predict the value or the existence of a critical voltage at which evolution becomes non-stationary.

Pressure-Induced Migration of Ferroelectric Interfaces

1994 ◽  
Vol 357 ◽  
Author(s):  
Alex Gordon ◽  
Simon Dorfman
Keyword(s):  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Landau Theory ◽  
Interface Velocity ◽  
Time Dependent ◽  
Ginzburg Landau ◽  
Suggested Approach ◽  
First Order ◽  
Temperature And Pressure ◽  
Kinetics Of

AbstractThe study of the migration of the first-order paraelectric-ferroelectric interfaces in BaTiO3 under the hydrostatic pressure is provided in the framework of the time-dependent Ginzburg-Landau theory. The analytical solution describing the interphase boundary is applied for the calculations of its width and velocity at different pressures. The calculations are based on the experimental data for BaTiO3. The parameters of the power law of the temperature and pressure dependences of the interface velocity under the temperature and pressure were obtained. Using the BaTiO3 example we illustrate the ability of the suggested approach in the description of the kinetics of the first-order ferroelectric phase transition in perovskites.

Proximity effect enhancement induced by a superconducting anti-dot

2014 ◽  
Vol 28 (31) ◽  
pp. 1450242
Author(s):  
Sindy J. Higuera ◽  
Miryam R. Joya ◽  
J. Barba-Ortega
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Proximity Effect ◽  
Magnetization Curve ◽  
Order Parameter ◽  
Proximity Effects ◽  
Time Dependent ◽  
Critical Fields ◽  
Ginzburg Landau ◽  
Ginzburg Landau Equations

In this work, we study the proximity and pinning effects of a rectangular superconducting anti-dot on the magnetization curve of a mesoscopic sample. We solve the nonlinear time-dependent Ginzburg–Landau equations for a superconducting rectangle in the presence of a magnetic field applied perpendicular to its surface. The pinning effects are determined by the number of vortices into the anti-dot. We calculate the order parameter, vorticity, magnetization and critical fields as a function of the external magnetic field. We found that the size and nature of the anti-dot strongly affect the magnetization of the sample. The results are discussed in framework of pinning and proximity effects in mesoscopic systems.

Superconducting state in a circular SQUID shaped mesoscopic film

2014 ◽  
Vol 28 (29) ◽  
pp. 1450230
Author(s):  
J. Barba-Ortega ◽  
Jose L. Aguilar ◽  
Jesús D. González
Keyword(s):  
Thin Film ◽  
Boundary Conditions ◽  
Superconducting State ◽  
Magnetization Curve ◽  
Order Parameter ◽  
Landau Theory ◽  
Time Dependent ◽  
Ginzburg Landau ◽  
Mesoscopic Superconductor ◽  
Parameter Profile

Using a thin-film approach to the time-dependent Ginzburg–Landau theory, we have studied the magnetization and order parameter profile in a thin mesoscopic superconductor in the so-called SQUID geometry. Our sample is circular with a hole at the center connected to the outer rim by a very thin slit. We have also studied the influence of the boundary conditions in the thin slit on the magnetization curve of the sample.

Time-dependent Landau theory for order/disorder processes in minerals

1989 ◽  
Vol 53 (372) ◽  
pp. 483-504 ◽  
Author(s):  
M. A. Carpenter ◽  
E. Salje
Keyword(s):  
Order Parameter ◽  
Driving Forces ◽  
Landau Theory ◽  
Landau Equation ◽  
Excess Entropy ◽  
Time Dependent ◽  
Specific Rate ◽  
Ginzburg Landau ◽  
Rate Laws ◽  
Image Position

AbstractRecent advances in the use of time-dependent order parameter theory to describe the kinetics of order/disorder transitions are reviewed. The time dependence of a macroscopic order parameter, Q, follows, to a good approximation:For systems in which the order parameter has a long correlation length (large ξ) and is not conserved (small ξC), the Ginzburg-Landau equation provides a general kinetic solution:Specific rate laws can be derived from this general solution depending on whether the crystals remain homogeneous with respect to the order parameter, Q. The advantages of the overall approach are, firstly, that it does not depend on the detailed structure of the material being examined; secondly, that the order parameter can be followed experimentally through its relationship with other properties, such as spontaneous strain, excess entropy, intensities of superlattice reflections, etc.; and, finally, that conventional Landau expansions in Q may be used to describe the thermodynamic driving forces.For a simple second-order transition in crystals which remain homogeneous in Q the rate law is:If the free energy of activation varies with the state of order of the crystal, this becomes:Simplifying assumptions can be introduced into the mathematics, or the integrals can be solved numerically. For crystals which remain homogeneous, the simplest solution valid only over small deviations from equilibrium is:For crystals which develop heterogeneities in Q, the rate laws change significantly and we find as an extreme case:where the A coefficient may be temperature dependent.Experimental data available for a limited number of minerals (omphacite, anorthite, albite, cordierite and nepheline) are used to demonstrate the practical implications of the overall approach. As anticipated from the theory, modulated structures commonly develop during kinetic experiments, the observed rate laws depend on whether the critical point of the ordering is located at the centre or boundary of the Brillouin zone, and the rate laws for ordering and disordering can be quite different. The importance of different length scales, not only in the different techniques for characterizing states of order (IR, NMR, calorimetry, X-ray diffraction, etc.) but also for interpreting observed mechanisms and rate laws, is also outlined.Use of the order parameter in Landau expansions and in Ginzburg-Landau rate laws provides, in principle, a means of predicting the equilibrium and non-equilibrium evolution of minerals in nature.

ON THE DYNAMICS OF LOW-TEMPERATURE MODELS FOR PHASE TRANSITIONS WITH CONSERVED ORDER PARAMETER

1988 ◽  
Vol 02 (06) ◽  
pp. 1537-1546 ◽  
Author(s):  
R. BAUSCH ◽  
R. KREE ◽  
A. LUSAKOWSKI ◽  
L. A. TURSKI
Keyword(s):  
Phase Transitions ◽  
Low Temperature ◽  
Order Parameter ◽  
Time Dependent ◽  
Ginzburg Landau ◽  
Landau Model ◽  
Non Linear

Starting from the time-dependent Ginzburg-Landau model, we derive dynamic versions of a non-linear σ-model and a drumhead model, both with conserved order parameter. In both cases there appears a non-ordering field that adiabatically follows the order parameter. In this way a constraint is imposed on the dynamics which guarantees consistency of conservation of the order parameter and the symmetries of the models.

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