Physics Colloquium with Prineha Narang on Predicting and Probing Carrier Interactions in Quantum Matter

The re-invigorated field of electron hydrodynamics in quantum matter has recently garnered considerable scientific interest, both due to its technological promise of designing near dissipation-less nanoelectronics, as well as its fundamental importance as an experimental probe of strong electron-electron interactions. Investigating the capacity to which observations of electron hydrodynamic flows can inform the nature of electron-electron interactions is particularly important and timely with the advent of spatially-resolved transport measurements which, having demonstrated the hallmark spatial signature of electron hydrodynamic channel flow, must now turn their attention to studying more spatially-complex geometries, enabling the observation of intricate fluid phenomena such as vortices. Recently we have explored the effects of crystal symmetry on electron fluid behaviors starting from the most general viscosity tensors in two and three dimensions, constrained only by crystal symmetry and thermodynamics. In our work we demonstrate the anomalous landscape for electron hydrodynamics in systems beyond graphene, highlighting that previously-thought exotic fluid phenomena can exist in both two-dimensional and anisotropic three-dimensional materials with or without breaking time-reversal symmetry. In this context, the first part of my talk will discuss our recent predictions of hydrodynamics beyond graphene1–4, especially the role of phonons in hydrodynamics 5–10. We identify phonon-mediated electron-electron interactions, computed with techniques developed in the group that I will discuss in this talk, as critical in a microscopic understanding of hydrodynamics. The second part of my talk will introduce a new theoretical and computational transport framework from our group, the SpaRTaNS (Spatially Resolved Transport of Nonequilibrium Species) framework. I will discuss applications of this method in nonequilibrium electron and phonon transport11, with an outlook on extending it to magnon transport in quantum matter.

References and links:
SpaRTaNS: Link to Github
1.    Varnavides, G., Jermyn, A. S., Anikeeva, P., Felser, C. & Narang, P. Electron hydrodynamics in anisotropic materials. Nat. Commun. 11, 1–6 (2020).
2.    Vool, U. et al. Imaging phonon-mediated hydrodynamic flow in WTe2. Nat. Phys. 17, 1216–1220 (2021).
3.    Wang, Y. et al. Generalized Design Principles for Hydrodynamic Electron Transport in Anisotropic Metals. arXiv:2109.00550 [cond-mat.mtrl-sci] (2021). In press at Phys. Rev. Materials.
4.    Varnavides, G., Jermyn, A. S., Anikeeva, P. & Narang, P. Probing carrier interactions using electron hydrodynamics. arXiv:2204.06004 [cond-mat.mtrl-sci] (2022). Under review.
5.    Osterhoudt, G. B. et al. Evidence for Dominant Phonon-Electron Scattering in Weyl Semimetal WP2. Physical Review X vol. 11 (2021).
6.    Coulter, J. et al. Uncovering electron-phonon scattering and phonon dynamics in type-I Weyl semimetals. Phys. Rev. B Condens. Matter 100, 220301 (2019).
7.    Garcia, C. A. C., Nenno, D. M., Varnavides, G. & Narang, P. Anisotropic phonon-mediated electronic transport in chiral Weyl semimetals. Phys. Rev. Materials 5, L091202 (2021).
8.    van Delft, M. R. et al. Sondheimer oscillations as a probe of non-ohmic flow in WP2 crystals. Nat. Commun. 12, 4799 (2021).
9.    Coulter, J., Sundararaman, R. & Narang, P. Microscopic origins of hydrodynamic transport in the type-II Weyl semimetal WP2. Phys. Rev. B Condens. Matter 98, (2018).
10.    Varnavides, G., Wang, Y., Moll, P. J. W., Anikeeva, P. & Narang, P. Mesoscopic finite-size effects of unconventional electron transport in PdCoO2. Phys. Rev. Mater. 6, (2022).
11.    Varnavides, G., Jermyn, A. S., Anikeeva, P. & Narang, P. Nonequilibrium phonon transport across nanoscale interfaces. Phys. Rev. B Condens. Matter 100, 115402 (2019).