290S/290K Quantum Materials Seminar Speaker Georgios Varnavides (UC Berkeley) Wednesday, September 7 at 2 pm in Physics South 402

Time/Venue Wednesday, September 7 at 2 pm Pacific time in Physics North 402 and via Zoom:
https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09
Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
Title: Spatially-Resolved Transport Framework for Electron Hydrodynamics in Crystalline Solids
Abstract: Recent advances in spatially-resolved transport measurements have revealed that electrons in condensed matter can flow collectively, exhibiting fluid phenomena such as channel flow and vortices. These observations confirm theoretical predictions over half a century old, violating textbook descriptions which treat electron collisions akin to balls in a pinball machine, and hold promise in designing energy-efficient nanoelectronic devices.
The first part of this talk will introduce electron hydrodynamic flow, highlighting recent experimental observations in WTe2 and PdCoO2,  and illustrate the novel electronic transport phenomena introduced by preferred directions in crystalline solids, including anisotropic and non-dissipative viscous contributions.
In the second part of the talk, I will introduce a new spatially-resolved transport framework, and use it to investigate an intriguing conundrum. Namely, that despite the microscopic scattering differences between materials exhibiting electron hydrodynamics, the experimentally-accessible current densities all share remarkable similarities. By projecting the system’s conserved quantities, physically-plausible collision operators respecting crystal symmetries are constructed and used to quantify the variability of the macroscopic current density observables statistically.
I will conclude by presenting ongoing work at Berkeley, to develop new electron microscopy imaging modalities to image these non-uniform current densities with nanoscale spatial resolution, as-well as outlining future theoretical work in introducing the role of band-topology in these electron flows.