Breakdown of the Wiedemann-Franz law at the Lifshitz point of strained Sr${}_2$RuO${}_4$

Abstract

Strain tuning Sr${}_2$RuO${}_4$ through the Lifshitz point, where the Van Hove singularity of the electronic spectrum crosses the Fermi energy, is expected to cause a change in the temperature dependence of the electrical resistivity from its Fermi liquid behavior $\rho \sim T^2$ to $\rho \sim T^2\log \left(1/T\right)$, a behavior consistent with experiments by Barber et al. [Phys. Rev. Lett. 120, 076601 (2018)]. This expectation originates from the same multi-band scattering processes with large momentum transfer that were recently shown to account for the linear in $T$ resistivity of the strange metal Sr${}_3$Ru${}_2$O${}_7$. In contrast, the thermal resistivity ${\rho }_Q\equiv T/\kappa$, where $\kappa$ is the thermal conductivity, is governed by qualitatively distinct processes that involve a broad continuum of compressive modes, i.e. long wavelength density excitations in Van Hove systems. While these compressive modes do not affect the charge current, they couple to thermal transport and yield ${\rho }_Q\propto T^{3/2}$. As a result, we predict that the Wiedemann-Franz law in strained Sr${}_2$RuO${}_4$ should be violated with a Lorenz ratio $L\propto T^{1/2}\log \left(1/T\right)$. We expect this effect to be observable in the temperature and strain regime where the anomalous charge transport was established.

arXiv comment12 pages, 7 figures

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Cited by in corpus (8)

• Dynamical Mean Field Theory of Moiré Bilayer Transition Metal Dichalcogenides: Phase Diagram, Resistivity, and Quantum Criticality
• A Criterion for Strange Metallicity in the Lorenz Ratio
• Pairing at a single Van Hove point
• The Lorenz ratio as a guide to scattering contributions to Planckian transport
• Designing Topological High-Order Van Hove Singularities: Twisted Bilayer Kagomé
• Universal relations between thermoelectrics and noise in mesoscopic transport across a tunnel junction
• Multipolar Fermi Surface Deformations in Sr${}_2$RuO${}_4$ Probed by Resistivity and Sound Attenuation: A Window into Electron Viscosity and the Collision Operator
• Anisotropic scattering rates in strain-tuned Sr${}_2$RuO${}_4$