1,598 research outputs found
Bernoulli Potential, Hall Constant and Cooper Pairs Effective Masses in Disordered BCS Superconductors
It is analyzed what fundamental new information for the properties of the
superconductors can be obtained by systematic investigation of the Bernoulli
effect. It is shown that it is a tool to determine the effective mass of Cooper
pairs, the volume density of charge carriers, the temperature dependence of the
penetration depth and condensation energy. The theoretical results for
disordered and anisotropic gap superconductors are systematized for this aim.
For clean-anisotropic-gap superconductors is presented a simple derivation for
the temperature dependence of the penetration depthComment: 13 pages, 3 figures, LaTeX 2e, New figure and reference
The existence of a stable noncollinear phase in a Heisenberg model with a complex structure
We have analyzed the properties of a noncollinear magnetic phase obtained in
the mean-field analysis of the model of two coupled Heisenberg subsystems. The
domain of its existence and stability is narrow and depends on the ratio
between the averaged over nearest neighbours microscopic exchange parameters.Comment: 7 pages, miktex, 3 figure
Influence of the van Hove singularity on the specific heat jump in BCS superconductors
Within the weak-coupling BCS scheme we derive a general form of the
coefficients in the Ginzburg-Landau expansion of the free energy of a
superconductor for the case of a Fermi level close to a van Hove singularity
(VHS). A simple expression for the influence of the VHS on the specific heat
jump is then obtained for the case where gaps for different bands are distinct
but nearly constant at the corresponding sheets of the Fermi surface.Comment: 8 pages, 2 figures, LaTeX2
The 3d-to-4s-by-2p highway to superconductivity in cuprates
High-temperature superconductors are nowadays found in great variety and hold
technological promise. It is still an unsolved mystery that the critical
temperature T_c of the basic cuprates is so high. The answer might well be
hidden in a conventional corner of theoretical physics, overlooked in the
recent hunt for exotic explanations of new effects in these materials. A
forgotten intra-atomic s-d two-electron exchange in the Cu atom is found to
provide a strong (~eV) electron pairing interaction. A
Bardeen-Cooper-Schrieffer approach can explain the main experimental
observations and predict the correct d_{x^2-y^2} symmetry of the gap.Comment: 4 pages, 3 figures, LaTeX2
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