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arXiv · 1806.04094

Departure from the Wiedemann-Franz Law in WP$_2$ Driven by Mismatch in $T$-square Resistivity Prefactors

Alexandre Jaoui·Benoît Fauqué·Carl Willem Rischau·Alaska Subedi·Chenguang Fu·Johannes Gooth·Nitesh Kumar·Vicky Süß·Dmitrii L. Maslov·Claudia Felser·Kamran Behnia
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Abstract

The Wiedemann-Franz (WF) law establishes a link between heat and charge transport due to electrons in solids. The extent of its validity in presence of inelastic scattering is a question raised in different contexts. We report on a study of the electrical, $σ$, and thermal, $κ$, conductivities in WP$_2$ single crystals. The WF holds at 2 K, but a downward deviation rapidly emerges upon warming. At 13 K, there is an exceptionally large mismatch between Lorenz number and the Sommerfeld value. We show that this is driven by a fivefold discrepancy between the $T$-square prefactors of electrical and thermal resistivities, both caused by electron-electron scattering. This implies the existence of abundant small-scattering-angle collisions between electrons, due to strong screening. By quantifying the relative frequency of collisions conserving momentum flux, but degrading heat flux, we identify a narrow temperature window where the hierarchy of scattering times may correspond to the hydrodynamic regime.

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Alexandre Jaoui, Benoît Fauqué, Carl Willem Rischau, Alaska Subedi, Chenguang Fu, Johannes Gooth, Nitesh Kumar, Vicky Süß, Dmitrii L. Maslov, Claudia Felser, Kamran Behnia. 2018-12-17. Departure from the Wiedemann-Franz Law in WP$_2$ Driven by Mismatch in $T$-square Resistivity Prefactors. https://doi.org/10.1038/s41535-018-0136-x

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