Renormalization of Coulomb interactions in s-wave superconductor Na$_x$CoO$_2$

Keiji Yada; Hiroshi Kontani

doi:10.1016/j.jmmm.2006.10.689

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Renormalization of Coulomb interactions in s-wave superconductor Na$_x$CoO$_2$

Keiji Yada·Hiroshi Kontani

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Abstract

We study the renormalized Coulomb interactions due to retardation effect in Na$_x$CoO$_2$. Although the Morel-Anderson's pseudo potential for $a_{1g}$ orbital $μ^*_{a1g}$ is relatively large because the direct Coulomb repulsion $U$ is large, that for interband transition between $a_{1g}$ and $e_g'$ orbitals $μ^*_{a1g,eg'}$ is very small since the renormalization factor for pair hopping $J$ is square of that for $U$. Therefore, the s-wave superconductivity due to valence-band Suhl-Kondo mechanism will survive against strong Coulomb interactions. The interband hopping of Cooper pairs due to shear phonons is essential to understand the superconductivity in Na$_x$CoO$_2$.

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Keiji Yada, Hiroshi Kontani. 2006-07-01. Renormalization of Coulomb interactions in s-wave superconductor Na$_x$CoO$_2$. https://doi.org/10.1016/j.jmmm.2006.10.689

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