Propagation of shear stress in strongly interacting metallic Fermi liquids enhances transmission of terahertz radiation

TL;DR

This paper proposes that shear stress can propagate as transverse zero sound in strongly correlated electron systems, similar to neutral Fermi liquids, and suggests terahertz transmission experiments to detect this phenomenon.

Contribution

It extends the concept of transverse zero sound from neutral Fermi liquids to charged heavy-fermion materials, proposing a sensitive experimental detection method.

Findings

Shear stress propagation as transverse zero sound is likely in strongly correlated electron systems.

Terahertz transmission should be enhanced and show oscillations due to transverse zero sound.

Experimental setup can detect this phenomenon via interference effects.

Abstract

A highlight of Fermi-liquid phenomenology, as explored in neutral $^3$He, is the observation that in the collisionless regime shear stress propagates as if one is dealing with the transverse phonon of a solid. The existence of this $"$transverse zero sound$"$ requires that the quasiparticle mass enhancement exceeds a critical value. Could such a propagating shear stress also exist in strongly correlated electron systems? Despite some noticeable differences with the neutral case in the Galilean continuum, we arrive at the verdict that transverse zero sound should be generic. We present an experimental setup that should be exquisitely sensitive in this regard: the transmission of terahertz radiation through a thin slab of heavy-fermion material will be strongly enhanced at low temperature and accompanied by giant oscillations, which reflect the interference between light itself and the $"$material photon$"$ being the actual manifestation of transverse zero sound in the charged Fermi liquid.