AC FLUCTUATION CONDUCTIVITY IN TYPE-II SUPERCONDUCTORS

2012 ◽  
Vol 26 (22) ◽  
pp. 1250143
Author(s):  
BUI DUC TINH ◽  
LE MINH THU
Keyword(s):  
Magnetic Field ◽  
Gaussian Approximation ◽  
Thermal Fluctuations ◽  
Vortex Pinning ◽  
Abrikosov Vortex ◽  
Type Ii ◽  
Ginzburg Landau ◽  
Fluctuation Conductivity ◽  
Type Ii Superconductor ◽  
The Magnetic Field

We use the time-dependent Ginzburg–Landau to calculate AC fluctuation conductivity in type-II superconductor in 2D model under magnetic field. Thermal fluctuations are assumed to be strong enough to melt the Abrikosov vortex lattice created by the magnetic field into a vibrating vortex liquid and marginalize the effects of the vortex pinning by inhomogeneities. The nonlinear interaction term in dynamics is treated within self-consistent Gaussian approximation. We obtain expressions the complex conductivity and resistivity summing all Landau levels which are applicable essentially to whole liquid phase and are compared to experimental data on high-Tc superconductor Bi 2 Sr 2 CaCu 2 O 8+δ.

scholarly journals Large enhancement of conductivity in a strongly layered type-II superconductor with an artificial pinning array

2020 ◽  
Vol 2020 (4) ◽  
Author(s):  
Bui Duc Tinh
Keyword(s):  
Landau Equation ◽  
Thermal Fluctuations ◽  
Energy Scale ◽  
Time Dependent ◽  
Type Ii ◽  
Ginzburg Landau ◽  
Fluctuation Conductivity ◽  
Ginzburg Landau Equation ◽  
Type Ii Superconductor ◽  
Large Enhancement

Abstract We use the time-dependent Ginzburg–Landau equation to describe a type-II superconductor in a magnetic field in the presence of both strong thermal fluctuations and an artificial pinning array. Thermal fluctuations are represented by the Langevin white noise. The layered structure of the superconductor is taken into accounted with the Lawrence–Doniach model. The self-consistent Gaussian approximation is used to treat the nonlinear interaction term in the time-dependent Ginzburg–Landau equation. In the case of the $\delta $-function model for the pinning centers and the matching field, analytic expressions for the fluctuation electrical and thermoelectric conductivity are obtained. It is found that the fluctuations in electrical and thermoelectric conductivities increase with increasing pinning strength, and when the pinning strength comes near a critical value, the fluctuation conductivity is greatly enhanced. Our result shows that if a pinning array is added to a mixed state superconductor, the original properties of the superconductor are recovered. Physically, in the presence of thermal fluctuations, when the energy scale of the vortex lattice shear fluctuations becomes comparable to the pinning energy scale there is a large enhancement of the fluctuation conductivity in the presence of pinning.

The Nernst effect in layered superconductors under a magnetic field

2016 ◽  
Vol 30 (22) ◽  
pp. 1650281 ◽  
Author(s):  
Bui Duc Tinh ◽  
Le Minh Thu ◽  
Nguyen Quang Hoc
Keyword(s):  
Thermal Noise ◽  
Gaussian Approximation ◽  
Landau Levels ◽  
Recent Experimental Data ◽  
Type Ii ◽  
Nernst Effect ◽  
Ginzburg Landau ◽  
Type Ii Superconductor ◽  
Self Consistent ◽  
Tdgl Equation

We calculated the Nernst signal [Formula: see text], describing the Nernst effect in type-II superconductor in the vortex–liquid regime, by using the time-dependent Ginzburg–Landau (TDGL) equation with thermal noise. The nonlinear interaction term in the TDGL equation is treated within self-consistent Gaussian approximation. The expression of the Nernst signal [Formula: see text] including all the Landau levels is presented in explicit form which is applicable essentially to the whole phase. Our results are compared with the recent experimental data on high-[Formula: see text] superconductor.

Transport coefficients and Nernst signal of type-II superconductors under magnetic field

2016 ◽  
Vol 30 (03) ◽  
pp. 1550267
Author(s):  
Bui Duc Tinh ◽  
Nguyen Quang Hoc
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Gaussian Approximation ◽  
Strong Electric Field ◽  
Landau Equation ◽  
Transport Coefficients ◽  
Thermal Fluctuations ◽  
Landau Levels ◽  
Type Ii ◽  
High Electric Fields

In this paper, we have studied the transport properties in two-dimensional superconductors in the frame of the Langevin approach to the time dependent Ginzburg–Landau equation. The electrical and thermoelectric conductivity, resulting from thermal fluctuations of the superconducting order parameter, are computed in the self-consistent Gaussian approximation for an arbitrarily strong electric field and a magnetic field. The Nernst signal, describing the Nernst effect in type-II superconductor under a magnetic field, is also calculated in linear response limit. We obtain analytical expressions for the electrical conductivity, the thermoelectric conductivity and the Nernst signal summing all Landau levels without need to cutoff higher Landau levels to treat an arbitrary magnetic field. Our results indicate that the electrical and thermoelectric conductivity are suppressed in high electric fields and the Nernst signal is in good agreement with experimental data on [Formula: see text].

scholarly journals Reduced Embedded Magnetic Field in Type-II Superconductor of Finite Dimension

2020 ◽  
Author(s):  
Frances Zhu ◽  
Mason Peck ◽  
Laura Jones-Wilson
Keyword(s):  
Magnetic Field ◽  
Finite Dimension ◽  
Type Ii ◽  
Refined Model ◽  
Image Model ◽  
Type Ii Superconductor ◽  
Measured Field ◽  
The Magnetic Field

This work maps the magnetic field within a type-II superconductor of finite dimension that is magnetically flux-pinned. The measured field is lower in magnitude than anticipated from the frozen image model and changes shape dependent on the field-cooled image location. A proposed refined model more accurately reflects the measured field.

On the distribution of the magnetic field of the transport current in type-II superconductor

1979 ◽  
Vol 51 (2) ◽  
pp. K117-K119 ◽  
Author(s):  
N. Alekseevsky ◽  
E. Krasnopiorov ◽  
E. Trojnar ◽  
A. J. Zaleski
Keyword(s):  
Magnetic Field ◽  
Transport Current ◽  
Type Ii ◽  
Type Ii Superconductor ◽  
The Magnetic Field
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