Ginzburg-Landau Free Energy of Crystalline Color Superconductors: A Matrix Formalism from Solid-State Physics

The Ginzburg-Landau (GL) free energy of crystalline color superconductors is important for understanding the nature of the phase transition to the normal quark matter and predicting the preferred crystal structure. So far the GL free energy at zero temperature has only been evaluated up to the sixth order in the condensate. To give quantitative reliable predictions we need to evaluate the higher-order terms. In this work, we present a new derivation of the GL free energy by using the discrete Bloch representation of the fermion field. This derivation introduces a simple matrix formalism without any momentum constraint, which may enable us to calculate the GL free energy to arbitrary order by using a computer.     

Athermal resistance to interface motion in the phase-field theory of microstructure evolution

A method of introducing an athermal resistance to interface propagation for the Ginzburg-Landau (GL) approach to the first-order phase transformations (PTs) is developed. It consists of introducing oscillating fields of stresses (due to various defects or a Peierls barrier) or a jump in chemical energy. It removes some essential drawbacks in GL modeling: it arrests experimentally observed microstructures that otherwise converge to a single phase, and it reproduces rate-independent stress hysteresis. A similar approach can be applied for twinning, dislocations, and other PTs (e.g., electric and magnetic).     

Surface induced mixed state of a superconducting film

Presented in this paper is a theoretical analysis of a planar surface induced mixed state for a superconducting film in parallel applied field. An analytical solution of the internal magnetic field is obtained based on Saint-James and de Gennes' order parameter in a film. An expression of Gibbs free energy per unit volume without restriction of a geometry is derived from non-linear Ginzburg-Landau (GL) equation in terms of a renormalized GL parameter and a modified geometric factor. Based on the Gibbs free energy, a phase diagram of distinguishing a first and second order phase transition for a type I superconducting film is calculated. The numerical results for exact solutions of spatial variation of order parameter, current density and internal magnetic field in the film geometry in parallel applied field case are presented. Near the upper critical field, the first entry of an applied field in the film exhibits a laminar structure.     

Optimum projection pattern generation for grey-level coded structured light illumination systems

Structured light illumination (SLI) systems are well-established optical inspection techniques for noncontact 3D surface measurements. A common technique is multi-frequency sinusoidal SLI that obtains the phase map at various fringe periods in order to estimate the absolute phase, and hence, the 3D surface information. Nevertheless, multi-frequency SLI systems employ multiple measurement planes (e.g. four phase shifted frames) to obtain the phase at a given fringe period. It is therefore an age old challenge to obtain the absolute surface information using fewer measurement frames. Grey level (GL) coding techniques have been developed as an attempt to reduce the number of planes needed, because a spatio-temporal GL sequence employing p discrete grey-levels and m frames has the potential to unwrap up to p^m fringes. Nevertheless, one major disadvantage of GL based SLI techniques is that there are often errors near the border of each stripe, because an ideal stepwise intensity change cannot be measured. If the step-change in intensity is a single discrete grey-level unit, this problem can usually be overcome by applying an appropriate threshold. However, severe errors occur if the intensity change at the border of the stripe exceeds several discrete grey-level units. In this work, an optimum GL based technique is presented that generates a series of projection patterns with a minimal gradient in the intensity. It is shown that when using this technique, the errors near the border of the stripes can be significantly reduced. This improvement is achieved with the choice generated patterns, and does not involve additional hardware or special post-processing techniques. The performance of that method is validated using both simulations and experiments. The reported technique is generic, works with an arbitrary number of frames, and can employ an arbitrary number of grey-levels.     

Effect of in-plane vortex coupling on Hall conductivity in high-Tc superconducting thin films

The controversial pinning dependence of the Hall conductivity (σ_xy) is studied in the vortex-liquid phase of high-T_c superconducting thin films. A strong pinning dependence of σ_xy is found to be triggered by a crossover from a regular liquid to the glassy liquid (GL) where vortices remain coupled in ab-plane. This result suggests that a non-linear effect in the GL region needs to be considered to account for the behavior of σ_xy in the whole vortex-liquid phase.     

Evolution from BCS to BEC superfluidity in p-wave Fermi gases

We consider the evolution of superfluid properties of a three-dimensional p-wave Fermi gas from a weak coupling Bardeen-Cooper-Schrieffer (BCS) to strong coupling Bose-Einstein condensation (BEC) limit as a function of scattering volume. At zero temperature, we show that a quantum phase transition occurs for p-wave systems, unlike the s-wave case where the BCS to BEC evolution is just a crossover. Near the critical temperature, we derive a time-dependent Ginzburg-Landau (GL) theory and show that the GL coherence length is generally anisotropic due to the p-wave nature of the order parameter, and becomes isotropic only in the BEC limit.     

Specific phase transition in superconductors of smallκ

A specific phase transition at which the superconductivity changes its order due to increasing alloy concentration has been observed. The values of the critical temperature, of the critical fields, of the GL parameter and the critical concentration have been determined.     

Evaluation of gap length fluctuation with harmonic analysis method

Gap length (GL) of reading head is one of the most critical parameters for high-density magnetic recording systems. A novel method is proposed for quantitative evaluation of the GL fluctuation among a batch of magneto-resistive/giant magneto-resistive heads with same structure design. The method works at head-gimbal assembly level and the evaluation can be done with any read/write analysis equipment. The testing process is based on harmonic analysis of the readback signal. The testing system consists of a selected reference head and sample heads for evaluation. A GL variation function is introduced for the evaluation of GL deviation between the reference head and sample head. This method proved to be easy for implementation and results suggest that variation of GL is considerable and has obvious effect on recording performance in high recording density systems.     

Concept of infrared photodetector based on graphene–graphene nanoribbon structure

We study the mechanisms of photoconductivity in graphene layer–graphene nanoribbon–graphene layer (GL–GNR–GL) structures with the i-type gapless GL layers as sensitive elements and I-type GNRs as barrier elements. The effects of both an increase in the electron and hole densities under infrared illumination and the electron and hole heating and cooling in GLs are considered. The device model for a GL–GNR–GL photodiode is developed. Using this model, the dark current, photocurrent, and responsivity are calculated as functions of the structure parameters, temperature, and the photon energy. The transition from heating of the electron–hole plasma in GLs to its cooling by changing the incident photon energy can result in the change of the photoconductivity sign from positive to negative. It is demonstrated that GL–GNR–GL photodiodes can be used in effective infrared and terahertz detectors operating at room temperature. The change in the photoconductivity sign can be used for the discrimination of the incident radiation with the wavelength 2–3 μm and 8–12 μm.     

Exact periodic and explicit solutions of the conformable time fractional Ginzburg Landau equation

The Ginzburg–Landau (GL) equation is one of the most important nonlinear equation in physics. It is used to model a vast variety of phenomena in physics like nonlinear waves, second order phase transitions, Bose–Einstein condensation, superfluidity, superconductivity, liquid crystals and strings in field theory. In this work, new exact, periodic and explicit solutions of a time fractional GL equation involving conformable fractional derivatives with Kerr law nonlinearity have been found. The Kerr law nonlinearity is due to the non-harmonic motion of electrons under the influence of an applied field. To determine the solution of the model, we have employed a couple of integration algorithms, solitary wave ansatz and \(\exp (-\varphi ({\chi }\))) methods. New periodic and hyperbolic soliton solutions are found as well as the constraint condition for the existence of the solution.     

NEB NONLINEAR σ MODELS ON SYMMETRIC SPACES

Two new nonlinear σ models, defined on the symmetric coset spaces GL (n,c). ⊕ GL(n,c)/GL (n,c) and GL (n,c)/U(n) respectively, are formulated in this paper.The latter may be useful in discus-sing the four-dimensional Yang-Mills fields.     

Existence criteria and validity of plate models for graphene-like materials

Graphene-like(GL) materials have enriched the application prospects of two-dimensional materials by virtue of their various structures and properties. However, the following theoretical issues remain unsolved: how can stable GL materials exist and is plate idealization valid for any GL materials? Here we answer these questions based on an atomistic potential-based approach.The existence criteria for GL materials with three common structures, including planar honeycomb(PH), buckled honeycomb(BH), and honeycomb MX_2(2 H-MX_2) structures, were established. Moreover, the validity of classic linear-elastic plate models for these materials was examined. A validity factor, which represents the validity of using thin plate models to investigate the overall mechanical response of GL sheets, was defined. We determined that 2 H-MX_2 sheets can approximately be modeled as thin plates for arbitrary loadings, unlike PH and BH sheets.     

Ginzburg-Landau theory of a supersolid

We develop a simple Ginsburg-Landau theory to study all the possible phases and phase transitions in 4He, analyze the condition for the existence of the supersolid (SS) and map out its global phase diagram from a unified framework. If the condition favors the existence of the SS, we use the GL theory to address several experimental facts and also make some predictions that are amenable to experimental tests. A key prediction is that the x-ray scattering intensity from the SS ought to have an additional modulation over that of the normal solid. The modulation amplitude is proportional to the nonclassical rotational-inertial observed in the torsional oscillator experiments.     

荧光光谱法研究黄豆黄素与牛血清白蛋白的相互作用

用荧光光谱法在pH 7.4的PBS中研究了黄豆黄素(Glycitein,GL)与牛血清白蛋白(Bovine serum albumin,BSA)分子之间的相互作用方式及机理.结果表明GL可静态猝灭BSA的内源荧光.310K和315K的结合位点数与表观结合常数分别为1.30,8.09×104L·mol-1和1.73,5....     

Mechanism of the acidic hydrolysis of epichlorohydrin

The present studies show that the currently accepted scheme for the hydrolysis of epichlorohydrin (ECH) needs to be extended by an additional path which makes allowance for the formation and decomposition of glycidol (GL). It was shown experimentally and through UB3LYP/6‐11 + +G(3D,P) calculations that the formation of 3‐chloro‐1,2‐propanediol (MCPD) from ECH should also take into account GL formation as an intermediate product. A modified mechanism for the course of ECH hydrolysis in acidic and neutral medium is proposed. It was shown that ECH hydrolysis in acidic medium in the presence of chloride ions also results in the formation of 1,3‐dichloro‐2‐propanol (DCPD) in addition to GL and MCPD. The possibility of a parallel pathway for water molecule addition to epichlorohydrin was shown which as a consequence led to the parallel appearance of GL and MCPD. It was confirmed by kinetic calculations that the state of equilibrium, reached in the process of ECH chlorination, did not result in GL formation. However, its appearance in the reaction mechanism has been ignored in the literature thus far. Copyright © 2011 John Wiley & Sons, Ltd.     

Lifshitz tricritical point and its relation to the FFLO superconducting state

We study the phase diagram of spatially inhomogeneous Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) superconducting state using the Ginzburg–Landau (GL) free energy, derived from the microscopic Hamiltonian of the system, and notice that it has a very clear Lifshitz tricritical point. We find the specific heat jumps abruptly near the first-order line in the emergent phase diagram which is very similar to the recent experimental observation in layered organic superconductor. Comparison with experimental data allows us to obtain quantitative relations between the parameters of phenomenological free energy. The region of the phase diagram where the specific heat jumps can be probed by doing a dynamical analysis of the free energy.     

A set of new nucleon coupling constants and the proto neutron star matter

Using a new set of nucleon coupling constants CZ11 the properties of a proto neutron star are examined within the framework of the relativistic mean-field theory for the baryon octet system.It is found that the relative number density of Λ,Ξ-,and Ξ0 for CZ11 are all smaller than those for GL97 and for both CZ11 and GL97,Σ-,Σ0,and Σ+ do not appear.It is also found that the pressure and the maximum mass for CZ11 are all smaller than those for GL97.The maximum mass for CZ11 decreases by approximately 9 percent compared with that for GL97.     

Extended Ginzburg-Landau formalism for two-band superconductors

Recent observation of unusual vortex patterns in MgB(2) single crystals raised speculations about possible "type-1.5" superconductivity in two-band materials, mixing the properties of both type-I and type-II superconductors. However, the strict application of the standard two-band Ginzburg-Landau (GL) theory results in simply proportional order parameters of the two bands-and does not support the "type-1.5" behavior. Here we derive the extended GL formalism (accounting all terms of the next order over the small τ=1-T/T(c) parameter) for a two-band clean s-wave superconductor and show that the two condensates generally have different spatial scales, with the difference disappearing only in the limit T→T(c). The extended version of the two-band GL formalism improves the validity of GL theory below T(c) and suggests revisiting the earlier calculations based on the standard model.     

Charge profile in vortices

The electric charge density in the vortex lattice of superconductors is studied within the Ginzburg-Landau (GL) theory. We show that the electrostatic potential varphi is proportional to the GL function, varphi /psi/2-/psi(infinity)/2. Numerical results for the triangular vortex lattice are presented.