Seminár z fyziky tuhých látok - František Herman

v piatok 29.3.2019 o 14:00 hod. v miestnosti F2/272

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Prednášajúci: František Herman (ETH Zürich)

Názov: Deviation from the Fermi-Liquid Transport Behavior in the Vicinity of a Van Hove Singularity

Termín: 29.3.2019, 14:00 hod., F2/272

Abstrakt:
Recent experiments revealed non-Fermi liquid resistivity in the unconventional superconductor Sr₂RuO₄ when strain pushes one of the Fermi surfaces close to a van Hove singularity. The origin of this behavior and whether it can be understood from a picture of well defined quasi-particles is unclear. We employ a comprehensive numerical Boltzmann transport analysis beyond the single relaxation-time approximation based on a single band which undergoes a Lifshitz transition either due to uni-axial or epitaxial strain. Analytically investigating impurity scattering, valid for the lowest temperatures, we clarify the role of the diverging density of states together with the locally flat band at the point of the Lifshitz transition in the general case. In the numerical study, we find good qualitative agreement with resistivity measurements on uni-axially strained Sr₂RuO₄, including the temperature scaling and the temperature dependence of the resistivity peak. Our results imply that at least up to close to the Lifshitz transition, a description starting from well-defined quasi-particles holds. To test the validity of Boltzmann transport theory in the vicinity of a van Hove singularity, we provide further experimentally accessible parameters, such as thermal transport, Seebeck coefficient and Hall resistivity and compare different strain scenarios.

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