Imaging phonon-mediated hydrodynamic flow in WTe2

In the presence of interactions, electrons in condensed-matter systems can behave hydrodynamically, exhibiting phenomena associated with classical fluids, such as vortices and Poiseuille flow(1-3). In most conductors, electron-electron interactions are minimized by screening effects, hindering the search for hydrodynamic materials; however, recently, a class of semimetals has been reported to exhibit prominent interactions(4,5). Here we study the current flow in the layered semimetal tungsten ditelluride by imaging the local magnetic field using a nitrogen-vacancy defect in a diamond. We image the spatial current profile within three-dimensional tungsten ditelluride and find that it exhibits non-uniform current density, indicating hydrodynamic flow. Our temperature-resolved current profile measurements reveal a non-monotonic temperature dependence, with the strongest hydrodynamic effects at approximately 20 K. We also report ab initio calculations showing that electron-electron interactions are not explained by the Coulomb interaction alone, but are predominantly mediated by phonons. This provides a promising avenue in the search for hydrodynamic flow and prominent electron interactions in high-carrier-density materials.

Automated summary

In this study, current flow in the layered semimetal tungsten ditelluride was investigated by imaging the local magnetic field, revealing non-uniform current density indicative of hydrodynamic flow, with the strongest effects observed around 20 K. Ab initio calculations suggest that electron-electron interactions are predominantly mediated by phonons rather than solely the Coulomb interaction, offering a promising avenue for the search for hydrodynamic flow and prominent electron interactions in high-carrier-density materials.