Two Bounds on the Maximum Phonon-Mediated Superconducting Transition Temperature
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arXiv
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| Format: | Preprint |
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2006
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| _version_ | 1866915535263891456 |
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| author | Moussa, Jonathan E. Cohen, Marvin L. |
| author_facet | Moussa, Jonathan E. Cohen, Marvin L. |
| contents | Two simple bounds on the $T_c$ of conventional, phonon-mediated superconductors are derived within the framework of Eliashberg theory in the strong coupling regime. The first bound is set by the total electron-phonon coupling available within a material given the hypothetical ability to arbitrarily dope the material. This bound is studied by deriving a generalization of the McMillan-Hopfield parameter, $\widetildeη(E)$, which measures the strength of electron-phonon coupling including anisotropy effects and rigid-band doping of the Fermi level to $E$. The second bound is set by the softening of phonons to instability due to strong electron-phonon coupling with electrons at the Fermi level. We apply these bounds to some covalent superconductors including MgB$_2$, where $T_c$ reaches the first bound, and boron-doped diamond, which is far from its bounds. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_cond_mat_0607832 |
| institution | arXiv |
| publishDate | 2006 |
| record_format | arxiv |
| spellingShingle | Two Bounds on the Maximum Phonon-Mediated Superconducting Transition Temperature Moussa, Jonathan E. Cohen, Marvin L. Superconductivity Two simple bounds on the $T_c$ of conventional, phonon-mediated superconductors are derived within the framework of Eliashberg theory in the strong coupling regime. The first bound is set by the total electron-phonon coupling available within a material given the hypothetical ability to arbitrarily dope the material. This bound is studied by deriving a generalization of the McMillan-Hopfield parameter, $\widetildeη(E)$, which measures the strength of electron-phonon coupling including anisotropy effects and rigid-band doping of the Fermi level to $E$. The second bound is set by the softening of phonons to instability due to strong electron-phonon coupling with electrons at the Fermi level. We apply these bounds to some covalent superconductors including MgB$_2$, where $T_c$ reaches the first bound, and boron-doped diamond, which is far from its bounds. |
| title | Two Bounds on the Maximum Phonon-Mediated Superconducting Transition Temperature |
| topic | Superconductivity |
| url | https://arxiv.org/abs/cond-mat/0607832 |