Purity-dependent Lorenz number, electron hydrodynamics and electron-phonon coupling in WTe${}_2$

Abstract

We present a study of electrical and thermal transport in Weyl semimetal WTe${}_2$ down to 0.3 K. The Wiedemann-Franz law holds below 2 K and a downward deviation starts above. The deviation is more pronounced in cleaner samples, as expected in the hydrodynamic picture of electronic transport, where a fraction of electron-electron collisions conserve momentum. Phonons are the dominant heat carriers and their mean-free-path do not display a Knudsen minimum. This is presumably a consequence of weak anharmonicity, as indicated by the temperature dependence of the specific heat. Frequent momentum exchange between phonons and electrons leads to quantum oscillations of the phononic thermal conductivity. Bloch-Grüneisen picture of electron-phonon scattering breaks down at low temperature when Umklapp ph-ph collisions cease to be a sink for electronic flow of momentum. Comparison with semi-metallic Sb shows that normal ph-ph collisions are amplified by anharmonicity. In both semimetals, at cryogenic temperature, e-ph collisions degrade the phononic flow of energy but not the electronic flow of momentum.

6 pages, 4 figures, Supplemental Materials included

References in corpus (26)

• Type-II Weyl Semimetals
• Titanic Magnetoresistance in WTe2
• Observation of the Dirac fluid and the breakdown of the Wiedemann-Franz law in graphene
• Electrical and Thermal Transport at the Planckian Bound of Dissipation in the Hydrodynamic Electron Fluid of WP2
• Quantum oscillations, thermoelectric coefficients and the Fermi surface of semi-metallic WTe2
• Phonon hydrodynamics and ultrahigh-room-temperature thermal conductivity in thin graphite
• Drastic pressure effect on the extremely large magnetoresistance in WTe2: quantum oscillation study
• Scalable T^2 resistivity in a small single-component Fermi surface
• Imaging phonon-mediated hydrodynamic flow in WTe2
• Thermal transport and phonon hydrodynamics in strontium titanate
• Departure from the Wiedemann-Franz Law in WP${}_2$ Driven by Mismatch in $T$-square Resistivity Prefactors
• Violation of the Wiedemann-Franz law in clean graphene layers
• Quantized Thermoelectric Hall Effect Induces Giant Power Factor in a Topological Semimetal
• Transport properties of strongly coupled electron-phonon liquids
• Direct evidence for charge compensation induced large magnetoresistance in thin WTe2
• Colossal Nernst power factor in topological semimetal NbSb${}_2$
• T-square resistivity without Umklapp scattering in dilute metallic Bi${}_2$O${}_2$Se
• Electron-phonon hydrodynamics
• Heat Transport as a Probe of Electron Scattering by Spin Fluctuations: the Case of Antiferromagnetic CeRhIn5
• Uncovering Electron-Phonon Scattering and Phonon Dynamics in Type-I Weyl Semimetals
• Thermal resistivity and hydrodynamics of the degenerate electron fluid in antimony
• On the origin and the amplitude of T-square resistivity in Fermi liquids
• Magnetoresistance of semi-metals: the case of antimony
• Lorentz ratio of a compensated metal
• Thermal Conductivity Tensor in YBa${}_2$Cu${}_3$O${}_{7-x}$: Effects of a Planar Magnetic Field
• T-square dependence of the electronic thermal resistivity in metallic strontium titanate

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