Title of article :
Kinks and d-waves from phonons: The intermediate coupling story Original Research Article
Author/Authors :
J.P. Hague، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2008
Pages :
4
From page :
2982
To page :
2985
Abstract :
I present results from an approach that extends the Eliashberg theory by systematic expansion in the vertex function; an essential extension at large phonon frequencies, even for weak coupling. In order to deal with computationally expensive double sums over momenta, a dynamical cluster approximation (DCA) approach is used to incorporate momentum dependence into the Eliashberg equations. First, I consider the effects of introducing partial momentum dependence on the standard Eliashberg theory using a quasi-local approximation; which I use to demonstrate that it is essential to include corrections beyond the standard theory when investigating d -wave states. Using the extended theory with vertex corrections, I compute electron and phonon spectral functions. A kink in the electronic dispersion is found in the normal state along the major symmetry directions, similar to that found in photo-emission from cuprates. The phonon spectral function shows that for weak coupling Wλ<ω0Wλ<ω0, the dispersion for phonons has weak momentum dependence, with consequences for the theory of optical phonon mediated d -wave superconductivity, which is shown to be 2nd order in λλ. In particular, examination of the order parameter vs. filling shows that vertex corrections lead to d-wave superconductivity mediated via simple optical phonons. I map out the order parameters in detail, showing that there is significant induced anisotropy in the superconducting pairing in quasi-2D systems.
Keywords :
C. neutron scattering , D. Superconductivity , D. lattice dynamics , D. Electronic structure , C. Photoelectron spectroscopy
Journal title :
Journal of Physics and Chemistry of Solids
Serial Year :
2008
Journal title :
Journal of Physics and Chemistry of Solids
Record number :
1310524
Link To Document :
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