scholarly journals Variation of the extended s-wave superconducting order parameter: From s-wave to g-wave

2015 ◽  
Vol 29 (27) ◽  
pp. 1550163
Author(s):  
H. Chung ◽  
N. Kim ◽  
H. Kim
Keyword(s):  
Fermi Surface ◽  
Density Of States ◽  
Power Law ◽  
Order Parameter ◽  
Superconducting Order Parameter ◽  
Text Line ◽  
Superconducting Properties ◽  
Detailed Structure ◽  
S Wave ◽  
Model Order

We investigate evolution of properties of an extended [Formula: see text]-wave superconductor, when the order parameter varies from an [Formula: see text]-wave to a [Formula: see text]-wave continuously, by using a model order parameter [Formula: see text]. The evolution of the gap amplitude, the density of states and the specific heat are mainly focused on. For [Formula: see text], due to the existence of a finite sized gap, the characteristic behaviors more or less follow those of the [Formula: see text]-wave. Sudden changes in the characteristic behaviors come out for [Formula: see text], due to appearances of nodes. For [Formula: see text], point nodes in the order parameter on the Fermi surface appear, while for [Formula: see text], line nodes appear. Although they are different kinds of nodes which would usually induce different power-law dependencies in superconducting properties, interestingly enough, they give rise to the same characteristic behavior. The detailed structure of the point nodes for [Formula: see text] is investigated, and it is explained why they lead to the same dependence as the line nodes.

ROLE OF HYBRIDIZATION IN THE SUPERCONDUCTING PROPERTIES OF AN EXTENDED d–p HUBBARD MODEL

2004 ◽  
Vol 18 (02) ◽  
pp. 241-252 ◽  
Author(s):  
E. J. CALEGARI ◽  
S. G. MAGALHÃES ◽  
A. A. GOMES
Keyword(s):  
Hubbard Model ◽  
Order Parameter ◽  
Superconducting Order Parameter ◽  
Superconducting Properties

In this work the variational Roth's approach previously developed by the present authors to describe cuprate systems is extended to include the superconducting properties. We extend the Beenen and Edwards approach by including the d–p hybridization. The role of the d–p hybridization in modifying the values of superconducting order parameter is then studied in terms of the adopted values of the parameters defining the Hamiltonian of the system.

scholarly journals Зависимость критической температуры цилиндрических сверхпроводников от граничных условий

2020 ◽  
Vol 62 (10) ◽  
pp. 1594
Author(s):  
А.Н. Лыков
Keyword(s):  
Boundary Conditions ◽  
Coherence Length ◽  
Order Parameter ◽  
Landau Theory ◽  
Small Diameter ◽  
Superconducting Order Parameter ◽  
Superconducting Properties ◽  
Ginzburg Landau

The paper presents the results of a study of the properties of long cylindrical superconductors with a diameter of the order of coherence length ξ, performed in the framework of the Ginzburg-Landau theory (GL). Boundary conditions of general form are used for solution of the GL equa-tion for superconducting order parameter. Using such boundary conditions allows us to take into account the influence of the cylinder boundary on its superconducting properties. This ap-proach is important for small-diameter cylinders, whose properties significantly depend on the properties of their boundaries.

THE FASCINATING NEW PHYSICS OF SOME OLD BCS SUPERCONDUCTORS

2002 ◽  
Vol 16 (20n22) ◽  
pp. 3134-3139
Author(s):  
V. BARZYKIN
Keyword(s):  
Time Reversal ◽  
Order Parameter ◽  
Coulomb Repulsion ◽  
New Physics ◽  
Superconducting Order Parameter ◽  
High Symmetry ◽  
New Materials ◽  
S Wave ◽  
Orbital Magnetism ◽  
Complicated Mechanism

We consider the pairing state due to the usual Bardeen-Cooper-Schrieffer mechanism in substances where the Fermi surface forms pockets around several points of high symmetry. The symmetry imposed on the multiple pocket positions can give rise to a multidimensional nontrivial superconducting order parameter. A complicated mechanism is not required for unusual superconductivity to exist, just the usual phonon attraction and Coulomb repulsion. Time reversal symmetry is broken, so the superconducting state also has orbital magnetism. In some sense, these superconductors are similar to superfluid3 He, which is known to have an 18-dimensional order parameter and a complicated phase diagram. We suggest several candidate substances where ordering of this kind may appear and discuss how these phases may be identified. Superconductivity in these new materials is expected to be much less sensitive to impurities than in other non s-wave superconductors.1

THE MICROSCOPIC APPROACH IN THE THEORY OF SUPERCONDUCTORS WITH A MANY-COMPONENT ORDER PARAMETER

1989 ◽  
Vol 03 (09) ◽  
pp. 1377-1401 ◽  
Author(s):  
Y.A. IZYUMOV ◽  
V.M. LAPTEV ◽  
V.N. SYROMYATNIKOV
Keyword(s):  
Fermi Surface ◽  
Order Parameter ◽  
Point Group ◽  
Energy Functional ◽  
Superconducting Order Parameter ◽  
Triplet States ◽  
Group Representations ◽  
Orbital Degeneracy ◽  
Electron States ◽  
Orbital Electron

In terms of the generalized Bardeen-Cooper-Schrieffer model for a superconductor with degenerate orbital electron states, we derive a Ginzburg-Landau energy functional with a microscopic deciphering of the coefficients involved. The superconducting order parameter is separated out by expanding the wave function of a Cooper pair in the basis functions of crystal point group irreducible representations. It is shown that a many-component superconducting order parameter may arise from the degeneracy of the electron states on the Fermi surface—either owing to the degeneracy of the orbital states or owing to the degeneracy over the arms of the star, or as a result of both degeneracies simultaneously. Allowance for the orbital degeneracy extends the physical basis on which superconducting modes are realized and perturbs the classification of singlet and triplet states according to even and odd point group representations. It is also shown that allowance for the orbital degeneracy may alter the conditions for the superconducting gap to go to zero in individual Fermi surface points or lines as compared with the conditions that follow from arm degeneracy alone.

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