Anharmonic theory of superconductivity in the high-pressure materials

Abstract

Electron-phonon superconductors at high pressures have displayed the highest values of critical superconducting temperature $T_c$ on record, now rapidly approaching room temperature. Despite the importance of high-$P$ superconductivity in the quest for room-temperature superconductors, a mechanistic understanding of the effect of pressure and its complex interplay with phonon anharmonicity and superconductivity is missing, as numerical simulations can only bring system-specific details clouding out key players controlling the physics. Here we develop a minimal model of electron-phonon superconductivity under an applied pressure which takes into account the anharmonic decoherence of the optical phonons. We find that $T_c$ behaves non-monotonically as a function of the ratio $\Gamma /{\omega }_0$, where $\Gamma$ is the optical phonon damping and ${\omega }_0$ the optical phonon energy at zero pressure and momentum. Optimal pairing occurs for a critical ratio $\Gamma /{\omega }_0$ when the phonons are on the verge of decoherence ("diffuson-like" limit). Our framework gives insights into recent experimental observations of $T_c$ as a function of pressure in the complex BCS material TlInTe${}_2$.

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Cited by in corpus (9)

• Ab initio structural optimization at finite temperatures based on anharmonic phonon theory: Application to the structural phase transitions of BaTiO${}_3$
• Possible enhancement of the superconducting $T_c$ due to sharp Kohn-like soft phonon anomalies
• Superconducting dome in ferroelectric-type materials from soft mode instability
• Anharmonic theory of superconductivity and its applications to emerging quantum materials
• Predicting plasticity of amorphous solids from instantaneous normal modes
• Pressure weakens coupling strength in In and Sn elemental superconductors
• Turning non-superconducting elements into superconductors by quantum confinement and proximity
• Estimation of Grüneisen parameter of high-entropy-alloy-type functional materials
• Pressure-induced concurrent amorphization and superconductivity in topological material NbNiTe5