Strong-Coupling Theory of Rattling-Induced Superconductivity

Abstract

In order to clarify the mechanism of the enhancement of superconducting transition temperature $T_{\mathrm{c}}$ due to anharmonic local oscillation of a guest ion in a cage composed of host atoms, i.e., {\it rattling}, we analyze the anharmonic Holstein model by applying the Migdal-Eliashberg theory. From the evaluation of the normal-state electron-phonon coupling constant, it is found that the strong coupling state is developed, when the bottom of a potential for the guest ion becomes wide and flat. Then, $T_{\mathrm{c}}$ is enhanced with the increase of the anharmonicity in the potential, although $T_{\mathrm{c}}$ is rather decreased when the potential becomes a double-well type due to very strong anharmonicity. From these results, we propose a scenario of anharmonicity-controlled strong-coupling tendency for superconductivity induced by rattling. We briefly discuss possible relevance of the present scenario with superconductivity in $\beta$-pyrochlore oxides.

8 pages, 6 figures

References in corpus (9)

• Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6
• Glasslike vs. crystalline thermal conductivity in carrier-tuned Ba8Ga16X30 clathrates (X = Ge, Sn)
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• Rattling-Induced Superconductiviy in the Beta-Pyrochlore Oxides AOs2O6
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• Kondo Effect in an Electron System with Dynamical Jahn-Teller Impurity
• Neutron Scattering Study of the Localized Mode in the beta-Pyrochlore Superconductors AOs2O6
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• Electron Mass Enhancement due to Anharmonic Local Phonons

Cited by in corpus (9)

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• Anharmonic theory of superconductivity and its applications to emerging quantum materials
• Strong-Coupling Superconductivity in BaPd2As2 Induced by Soft Phonons in the ThCr2Si2-type Polymorph
• Heavy-Electron Formation and Bipolaronic Transition in the Anharmonic Holstein Model
• Lattice Anharmonicity in BiS2-Based Layered Superconductor RE(O,F)BiS2 (RE = La, Ce, Pr, Nd)
• Spin dynamics of S-state ions in the filled skutterudites La1-xRx$Pt4Ge12 (R= Gd, Eu)
• Novel Rattling of K Atoms in Aluminium-Doped Defect Pyrochlore Tungstate
• Anomalous Isotope Effect in Rattling-Induced Superconductor