London Penetration Depthin λ(T) in Type 1.5 Superconductor by Ginzburg-Landau Approach

2013 ◽  
Vol 770 ◽  
pp. 291-294 ◽  
Author(s):  
N. Niyomsilpchai ◽  
A. Changjan ◽  
Pongkaew Udomsamuthirun
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Penetration Depth ◽  
Band Model ◽  
Type I ◽  
London Penetration Depth ◽  
Ginzburg Landau ◽  
Type Ii Superconductor ◽  
New Type ◽  
The Magnetic Field

The London penetration depth is the distance to which a magnetic field penetrates into a superconductor and becomes equal to 0.367879 times that of the magnetic field at the surface of the superconductor. The type 1.5 superconductor is the new type of superconductor that the value of Ginzburg-Landau parameter is between the type I and type II superconductor. In this paper, the London penetration depth of type 1.5 superconductor is studied by Ginzburg-Landau approach. The system of free energy of type 1.5 superconductor is assumed by modified the free energy of two-band model and theof type 1.5 superconductor is derived analytically. Finally, the temperature dependence of London penetration depth is investigated.

London Penetration Depth of Fe-Based Superconductors

2014 ◽  
Vol 979 ◽  
pp. 297-301 ◽  
Author(s):  
Arpapong Changjan ◽  
Pongkaew Udomsamuthirun
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Penetration Depth ◽  
Electrical Resistance ◽  
Critical Magnetic Field ◽  
London Penetration Depth ◽  
Iron Compounds ◽  
Ginzburg Landau ◽  
The Magnetic Field ◽  
Very High

Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature. Fe-based superconductors are superconductors whose containing iron compounds and having a very high critical magnetic field. London penetration depth can assist in the study of the behavior of the critical magnetic field. The London penetration depth is the distance to which a magnetic field penetrates into a superconductor and becomes equal to 0.367879 times that of the magnetic field at the surface of the superconductor. In this paper, the London penetration depth of Fe-based superconductors is studied by Ginzburg-Landau scenery. Free energy of Fe-based superconductors is assumed by modified the free energy of two-band magnetic superconductors model and theof Fe-based superconductors is derived analytically. Finally, the temperature dependence of is investigated and applied to Single-Crystal superconductors.

Superconductivity and nucleation from fractal anisotropy and product-like fractal measure

2021 ◽  
Vol 477 (2249) ◽  
pp. 20210065
Author(s):  
Rami Ahmad El-Nabulsi
Keyword(s):  
Density Wave ◽  
Spin Density Wave ◽  
Simultaneous Occurrence ◽  
Type I ◽  
London Penetration Depth ◽  
Ginzburg Landau ◽  
Fractal Measure ◽  
Heavy Doping ◽  
Physical Quantities ◽  
The Magnetic Field

Superconductivity is analysed based on the product-like fractal measure approach with fractal dimension α introduced by Li and Ostoja-Starzewski in their attempt to explore anisotropic fractal elastic media. Our study shows the emergence of a massless state at the boundary of the superconductor and the simultaneous occurrence of isothermal and adiabatic processes in the superconductor depending on the position of the electrons. Several physical quantities were found to be position-dependent comparable with those arising in heavy doping and p–n junction. At the boundary of the superconductor, a shrinkage of the magnetic field was observed, leading to a scenario equivalent to the Meissner–Ochsenfeld effect. An enhancement of the London penetration depth is revealed and such an improvement was observed in pnictides at the onset of commensurate spin-density-wave order inside the superconducting phase at zero temperature. The Bardeen–Cooper–Schrieffer theory was also analysed and the appearance of zero-energy states is detected. Nucleation of superconductivity in a bulk was also studied. The system acts as a quantum damped harmonic oscillator and our analysis showed that type-I superconductivity occurs when κ < 2 / ( 1 + α ) , whereas type II occurs for κ > 2 / ( 1 + α ) , where κ is the Ginzburg–Landau parameter. The transition at the passage from the ‘genuine’ to the ‘intermediate’ type-I estimates 0.767767 < α ≤ 1 .

scholarly journals Magnetoresistance peculiarities and magnetization of materials with two kinds of superconducting inclusions

2015 ◽  
Vol 33 (1) ◽  
pp. 73-81
Author(s):  
O. N. Shevtsova
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Penetration Depth ◽  
Coherence Length ◽  
Superconducting Phase ◽  
Type I ◽  
Temperature Conductivity ◽  
External Impact ◽  
Technological Processing ◽  
The Magnetic Field

AbstractLow-temperature properties of a crystal containing type I superconducting inclusions of two different materials have been studied. In the approximation assuming that the inclusions size is much smaller than the coherence length/penetration depth of the magnetic field, the theory of magnetoresistance of a crystal containing spherical superconducting inclusions of two different materials has been developed, and magnetization of crystals has been calculated. The obtained results can be used for correct explanation of the low temperature conductivity in binary and more complex semiconductors, in which precipitation of the superconducting phase is possible during the technological processing or under external impact.

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.

MAGNETIC FIELD DEPENDENCE OF CRITICAL CURRENTS IN SUPERCONDUCTING POLYCRYSTALS

1992 ◽  
Vol 06 (03) ◽  
pp. 161-169 ◽  
Author(s):  
K.I. KUGEL ◽  
T. YU. LISOVSKAYA ◽  
R.G. MINTS
Keyword(s):  
Magnetic Field ◽  
Magnetic Field Dependence ◽  
Asymptotic Form ◽  
Critical Currents ◽  
Transport Current ◽  
Wide Field ◽  
London Penetration Depth ◽  
Field Range ◽  
Crystallographic Axes ◽  
The Magnetic Field

We study the dependence of critical current j c on magnetic field H in superconducting polycrystals which are considered as systems of superconducting crystallites (isotropic or anisotropic) with Josephson contacts between them. Isotropy or anisotropy of contacts depends on the orientation of their crystallographic axes relatively to edges of contact planes. It is shown that for a system of randomly oriented isotropic contacts, the dependence j c (H) in a relatively wide field range has the asymptotic form j c ~( ln H)/H2. This differs drastically from j c (H) for single contacts. Anisotropy effects due to large differences in London penetration depth λ values corresponding to external magnetic field directed along different axes are analyzed in detail. It is shown that for uniaxal crystals with λ1=λ2≪λ3, this anisotropy leads to the relation [Formula: see text] for chaotic orientation of crystallites. The form of j c (H) curves for two different orientations of the magnetic field relatively to the transport current through the sample is found.

scholarly journals Theoretical Study of Upper Critical Magnetic Field (HC2) in Multiband Iron Based Superconductors

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Tsadik Kidanemariam ◽  
Gebregziabher Kahsay
Keyword(s):  
Magnetic Field ◽  
Phase Diagrams ◽  
Penetration Depth ◽  
Coherence Length ◽  
Symmetry Axis ◽  
Critical Magnetic Field ◽  
Ginzburg Landau ◽  
Iron Based Superconductors ◽  
Upper Critical Magnetic Field ◽  
Iron Based

This research work focuses on the theoretical investigation of the upper critical magnetic field,HC2; Ginzburg-Landau coherence length,ξGL(T); and Ginzburg-Landau penetration depth,λGL(T), for the two-band iron based superconductorsBaFe2(As1-xPx)2,NdO1-xFxFeAs, and LiFeAs. By employing the phenomenological Ginzburg-Landau (GL) equation for the two-band superconductorsBaFe2(As1-xPx)2,NdO1-xFxFeAs, and LiFeAs, we obtained expressions for the upper critical magnetic field,HC2; GL coherence length,ξGL; and GL penetration depth,λGL, as a function of temperature and the angular dependency of upper critical magnetic field. By using the experimental values in the obtained expressions, phase diagrams of the upper critical magnetic field parallel,HC2∥c, and perpendicular,HC2⊥c, to the symmetry axis (c-direction) versus temperature are plotted. We also plotted the phase diagrams of the upper critical magnetic field,HC2versus the angleθ. Similarly, the phase diagrams of the GL coherence length,ξGL, and GL penetration depth,λGL, parallel and perpendicular to the symmetry axis versus temperature are drawn for the superconductors mentioned above. Our findings are in agreement with experimental observations.

scholarly journals Radio Emission Model of a 'Typical' Pulsar

1987 ◽  
Vol 40 (6) ◽  
pp. 755 ◽  
Author(s):  
AZ Kazbegi ◽  
GZ Machabeli ◽  
G Melikidze
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Emission Model ◽  
Radio Waves ◽  
Resonance Case ◽  
Pulsar Magnetosphere ◽  
Pulsar Emission ◽  
Dipole Magnetic Field ◽  
New Type ◽  
The Magnetic Field

The generation of radio waves in the plasma of the pulsar magnetosphere is considered taking into account the inhomogeneity of the dipole magnetic field. It is shown that the growth rate of the instability of the electromagnetic waves calculated in the non-resonance case turns out to be of the order of 1/ TO (where TO is the time of plasma escape from the light cylinder). However, the generation of electromagnetic waves from a new type Cherenkov resonance is possible, occurring when the particles have transverse velocities caused by the drift due to the inhomogeneity of the magnetic field. Estimates show that the development of this type of instability is possible only for pulsars with ages which exceed 104 yr. We make an attempt to explain some peculiarities of 'typical' pulsar emission on the basis of the model developed.

ISING MODEL IN THE MAGNETIC FIELD iπkT/2

1988 ◽  
Vol 02 (03n04) ◽  
pp. 471-481 ◽  
Author(s):  
K. Y. LIN ◽  
F. Y. WU
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Ising Model ◽  
Zero Field ◽  
Two Dimensional ◽  
Anisotropic Interactions ◽  
The Magnetic Field ◽  
Explicit Expressions

It is shown that the free energy and the magnetization of an Ising model in the magnetic field H = iπkT/2 can be obtained directly from corresponding expressions of these quantities in zero field, provided that the latter are known for sufficiently anisotropic interactions. Using this approach we derive explicit expressions of the free energy and the magnetization at H = iπkT/2 for a number of two-dimensional lattices.

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