SEMINAIRE MATERIAUX QUANTIQUES
Groupe NFMQ, Laboratoire Léon Brillouin

Mercredi 9 Mars 2022 à 10h00
Lien visio : https://meet.goto.com/642029909

Pr. Alessio Zaccone
Université de Cambridge, Angleterre

Lattice Dynamics and Elasticity of Complex Materials: Implications for Novel Superconductors

While electrons in disordered systems have been studied early on leading to the Nobel prize in physics 1977 for Phil W. Anderson and Sir Neville Mott, a similar understanding of phonons and lattice dynamics of disordered (amorphous) and complex systems, or systems with strong anharmonicity, is still at its infancy. This field is currently blossoming due to its centrality in contemporary condensed matter physics and materials physics. In particular, to arrive at a deeper understanding of complex materials (e.g. polymers, metallic glasses, high-T/high-P superconductors) it is essential to develop a successful description of vibrational modes, soft modes, anharmonicity and elasticity/mechanical instabilities in these complex condensed matter systems [1-4]. I will briefly review our new understanding of phonons and elasticity in real complex solids, from the angle of my recent contributions to the field. In the main part of the talk, I will show how this understanding can lead to a theoretical framework which describes and rationalizes superconductivity in disordered systems such as disordered metallic alloys [5] as well as materials with strong anharmonicity [6] where properly accounting for anharmonic phonon damping within BCS theory leads to new, surprising effects [6]. I will then show how this framework can be extended to high-T superconductors at high pressures, which have currently achieved record high Tc at room temperature [7], and where anharmonicity also plays a crucial role. Finally, I show how the same theory can provide a simple theoretical description and understanding of the superconducting dome near ferroelectric-type phase transitions characterized by soft modes/structural instability [8].

References

• [1] A. Zaccone and E. Scossa-Romano, Phys. Rev. B 83, 184205 (2011)
• [2] M. Baggioli and A. Zaccone, Phys. Rev. Lett. 122, 145501 (2019)
• [3] M. Baggioli and A. Zaccone, Phys. Rev. Research 2, 013267 (2020)
• [4] A. Zaccone and K. Trachenko, PNAS 117, 19653 (2020)
• [5] A. Zaccone and M. Baggioli, PNAS 118 (5), e2022303118 (2021)
• [5] M. Baggioli, C. Setty and A. Zaccone, Phys. Rev. B 101, 214502 (2020)
• [6] C. Setty, M. Baggioli and A. Zaccone, Phys. Rev. B 102, 174506 (2020)
• [7] C. Setty, M. Baggioli and A. Zaccone, Phys. Rev. B 103, 094519 (2021).
• [8] C. Setty, M. Baggioli and A. Zaccone, arXiv:2110.08114 (2021)