620 research outputs found
Negative energy antiferromagnetic instantons forming Cooper-pairing "glue" and "hidden order" in high-Tc cuprates
An emergence of magnetic boson of instantonic nature, that provides a
Cooper-'pairing glue', is considered in the repulsive 'nested' Hubbard model of
superconducting cuprates. It is demonstrated, that antiferromagnetic instantons
of a spin density wave type may have negative energy due to coupling with
Cooper pair condensate. A set of Eliashberg-like equations is derived and
solved self-consistently, proving the above suggestion. An instantonic
propagator plays the role of Green function of pairing 'glue' boson.
Simultaneously, the instantons defy condensation of the mean-field SDW order.
We had previously demonstrated in analytical form \cite{2,3,4} that periodic
chain of instanton-anti-instanton pairs along the axis of Matsubara time has
zero scattering cross section for weakly perturbing external probes, like
neutrons, etc., thus representing a 'hidden order'. Hence, the two competing
orders, superconducting and antiferromagnetic, may coexist (below some Tc) in
the form of mean-field superconducting order, coupled to 'hidden'
antiferromagnetic one. This new picture is discussed in relation with the
mechanism of high temperature superconductivity
Spin-charge ordering induced by magnetic field in superconducting state: analytical solution in the two-dimensional self-consistent model
Solutions of the Bogoliubov-de Gennes equations for the two-dimensional
self-consistent Hubbard t-U-V model of superconductors with
symmetry of the order parameter in the presence of a magnetic field are found.
It is shown that spatial inhomogeneity of superconducting order parameter
results in the emergence of stripe-like domains that are stabilized by applied
magnetic field leading to emergence of space-modulated composite
spin-charge-superconducting order parameter.Comment: 4 figures. arXiv admin note: substantial text overlap with
arXiv:1111.413
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