Photogalvanic effect in hydrodynamic flows of nonreciprocal electron liquids

TL;DR

This paper investigates the nonlinear hydrodynamic electron transport in noncentrosymmetric conductors with broken TR symmetry, revealing a hydrodynamic analogue of the photogalvanic effect where AC fields generate a DC current influenced by nonreciprocity and flow geometry.

Contribution

It introduces a hydrodynamic framework for the photogalvanic effect in electron liquids, highlighting the roles of nonreciprocity and flow geometry in nonlinear transport phenomena.

Findings

DC current scales quadratically with AC electric field amplitude

Nonlocal hydrodynamic effects lead to super-extensive DC current at low frequencies

Hysteresis in current-voltage characteristics is affected by nonreciprocity

Abstract

We study nonlinear hydrodynamic electron transport driven by an AC electric field. In noncentrosymmetric conductors with broken time-reversal (TR) symmetry the nonlinear flow of such liquids is nonreciprocal, giving rise to a DC current $I^{DC}$ that is quadratic in the amplitude of the AC electric field. This is the hydrodynamic analogue of the linear photogalvanic effect (PGE), which arises in bulk noncentrosymmetric materials with broken TR symmetry. The magnitude of $I^{DC}$ depends on both the properties of the electron fluid and the geometry of the flow, and may be characterized by two dimensionless parameters: the nonreciprocity number $\mathcal{N}$, and the frequency-dependent vibrational number $\mathcal{R}$. Due to nonlocality of hydrodynamic transport, at low frequencies of the AC drive, $I^{DC}$ is super-extensive. The AC component of the electric current is likewise strongly affected by nonreciprocity: the hysteretic current-voltage dependence becomes skewed, which can be interpreted in terms of nonreciprocity of the memory retention time.