Hidden spin-current conservation in 2d Fermi liquids

TL;DR

This paper predicts regimes in 2D Fermi liquids where spin current is conserved, leading to unique spin wave phenomena and potential experimental signatures.

Contribution

It demonstrates that spin current conservation can occur broadly in 2D Fermi liquids and introduces new spin wave modes at high temperatures.

Findings

Spin current conservation can be achieved in 2D Fermi liquids.

Distinctive spin wave propagation at low temperatures.

Prediction of new spin-acoustic modes at high temperatures.

Abstract

We report the existence of regimes of the two dimensional Fermi liquid that show unusual conservation of the spin current and may be tuned by varying some parameter like the density of fermions. We show that for reasonable models of the effective interaction the spin current may be conserved in general in 2d, not only for a particular regime. Low temperature spin waves propagate distinctively in these regimes and entirely new ``spin-acoustic'' modes are predicted for scattering-dominated temperature ranges. These new high-temperature propagating spin waves provide a clear signature for the experimental search of such regimes.