Dec 8 – 10, 2020 Online only
Online event
Europe/Berlin timezone

Phonon renormalization explained by electron-momentum dependent electron-phonon coupling

Dec 10, 2020, 4:00 PM
15m
Online event

Online event

Talk DN: Materials DN2020: Materials

Speaker

Frank Weber (Karlsruhe Institute of Technology)

Description

Electron-phonon coupling, i.e., the scattering of lattice vibrations by electrons and vice versa, is a common phenomenon in solids and can lead to emergent ground states such as superconductivity and charge-density wave order. Signatures of strong electron-phonon coupling, e.g. softening and broadening of phonons on cooling, are typically assigned to the presence of nested parts of the Fermi surface or lattice anharmonicity. Here, we unravel a third scenario in the seminal strong-coupling material YNi$_2$B$_2$C. The three-dimensional Fermi surface features a large value of the electronic joint density-of-states but only fro a particular value of the electron out-of-plane momentum $k_z$. Using a combination of inelastic neutron scattering and angle-resolved photoemission spectroscopy analyzed based on ab-initio lattice dynamical calculations we show that this peak of the electronic joint density-of-states as function of $k_z$ is likely the origin for the spectacular phonon renormalization in YNi$_2$B$_2$C. Thus, our study rationalizes strong phonon anomalies in the absence of both classic, i.e. phonon-momentum dependent nesting and anharmonicity.

Primary authors

Mr Philipp Kurzhals (Karlsruhe Institute of Technology) Dr Geoffrey Kremer (University of Fribourg) Dr Thomas Jaouen (University of Fribourg) Dr Chris Nicholson (University of Fribourg) Dr Rolf Heid (Karlsruhe Institute of Technology) Dr Peter Nagel (Karlsruhe Institute of Technology) Dr John-Paul Castellan (Karlsruhe Institute of Technology) Dr Alexander Ivanov (Institut Laue Langevin) Dr Vladimir Strocov (Paul-Scherrer Institut) Prof. Claude Monney (University of Fribourg) Prof. Dmitry Reznik (University of Colorado at Boulder) Frank Weber (Karlsruhe Institute of Technology)

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