2,051 research outputs found
A hierarchy of models for type-II superconductors
A hierarchy of models for type-II superconductors is presented. Through appropriate asymptotic limits we pass from the mesoscopic Ginzburg-Landau model to the London model with isolated superconducting vortices as line singularities, to vortex-density models, and finally to macroscopic critical-state models
Orbitally limited pair-density wave phase of multilayer superconductors
We investigate the magnetic field dependence of an ideal superconducting
vortex lattice in the parity-mixed pair-density wave phase of multilayer
superconductors within a circular cell Ginzburg-Landau approach. In multilayer
systems, due to local inversion symmetry breaking, a Rashba spin-orbit coupling
is induced at the outer layers. This combined with a perpendicular paramagnetic
(Pauli) limiting magnetic field stabilizes a staggered layer dependent
pair-density wave phase in the superconducting singlet channel. The high-field
pair-density wave phase is separated from the low-field BCS phase by a
first-order phase transition. The motivating guiding question in this paper is:
what is the minimal necessary Maki parameter for the appearance of
the pair-density wave phase of a superconducting trilayer system? To address
this problem we generalize the circular cell method for the regular flux-line
lattice of a type-II superconductor to include paramagnetic depairing effects.
Then, we apply the model to the trilayer system, where each of the layers are
characterized by Ginzburg-Landau parameter , and a Maki parameter
. We find that when the spin-orbit Rashba interaction compares to the
superconducting condensation energy, the orbitally limited pair-density wave
phase stabilizes for Maki parameters .Comment: 13 pages, 7 figure
Ginzburg-Landau Like Theory for High Temperature Superconductivity in the Cuprates: Emergent d-wave Order
High temperature superconductivity in the cuprates remains one of the most
widely investigated, constantly surprising, and poorly understood phenomena in
physics. Here, we describe briefly a new phenomenological theory inspired by
the celebrated description of superconductivity due to Ginzburg and Landau and
believed to describe its essence. This posits a free energy functional for the
superconductor in terms of a complex order parameter characterizing it. We
propose, for superconducting cuprates, a similar functional of the complex, in
plane, nearest neighbor spin singlet bond (or Cooper) pair amplitude psi_ij. A
crucial part of it is a (short range) positive interaction between nearest
neighbor bond pairs, of strength J'. Such an interaction leads to nonzero long
wavelength phase stiffness or superconductive long range order, with the
observed d-wave symmetry, below a temperature T_c\simzJ' where z is the number
of nearest neighbours; it is thus an emergent, collective consequence. Using
the functional, we calculate a large range of properties, e.g. the pseudogap
transition temperature T* as a function of hole doping x, the transition curve
T_c(x), the superfluid stiffness rho_s(x,T), the specific heat (without and
with a magnetic field) due to the fluctuating pair degrees of freedom, and the
zero temperature vortex structure. We find remarkable agreement with
experiment. We also calculate the self energy of electrons hopping on the
square cuprate lattice and coupled to electrons of nearly opposite momenta via
inevitable long wavelength Cooper pair fluctuations formed of these electrons.
The ensuing results for electron spectral density are successfully compared
with recent ARPES experiments, and comprehensively explain strange features
such as temperature dependent Fermi arcs above T_c and the 'bending' of the
superconducting gap below T_c .Comment: 22 pages, 14 figures, to appear in Int J Mod Phys
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