A theory of superconductivity is presented where the effect of anharmonicity, as entailed in the acoustic, or optical, phonon damping, is explicitly considered in the pairing mechanism. The gap equation is solved including diffusive Akhiezer damping for longitudinal acoustic phonons or Klemens damping for optical phonons, with a damping coefficient which, in either case, can be directly related to the Gruneisen parameter and hence to the anharmonic coefficients in the interatomic potential. The results show that the increase of anharmonicity has a strikingly nonmonotonic effect on the critical temperature T-c. The optimal damping coefficient yielding maximum T-c is set by the velocity of the bosonic mediator. This theory may open up unprecedented opportunities for material design where T-c may be tuned via the anharmonicity of the interatomic potential, and presents implications for the superconductivity in the recently discovered hydrides, where anharmonicity is very strong and for which the anharmonic damping is especially relevant.

Anharmonic phonon damping enhances the Tc of BCS-type superconductors / C. Setty, M. Baggioli, A. Zaccone. - In: PHYSICAL REVIEW. B. - ISSN 2469-9950. - 102:17(2020 Nov 19). [10.1103/PhysRevB.102.174506]

Anharmonic phonon damping enhances the Tc of BCS-type superconductors

A. Zaccone
2020

Abstract

A theory of superconductivity is presented where the effect of anharmonicity, as entailed in the acoustic, or optical, phonon damping, is explicitly considered in the pairing mechanism. The gap equation is solved including diffusive Akhiezer damping for longitudinal acoustic phonons or Klemens damping for optical phonons, with a damping coefficient which, in either case, can be directly related to the Gruneisen parameter and hence to the anharmonic coefficients in the interatomic potential. The results show that the increase of anharmonicity has a strikingly nonmonotonic effect on the critical temperature T-c. The optimal damping coefficient yielding maximum T-c is set by the velocity of the bosonic mediator. This theory may open up unprecedented opportunities for material design where T-c may be tuned via the anharmonicity of the interatomic potential, and presents implications for the superconductivity in the recently discovered hydrides, where anharmonicity is very strong and for which the anharmonic damping is especially relevant.
Settore FIS/02 - Fisica Teorica, Modelli e Metodi Matematici
Settore FIS/03 - Fisica della Materia
19-nov-2020
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/793284
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