The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases

Patrick J Ledwith; Haoyu Guo; Leonid Levitov

doi:10.1016/j.aop.2019.167913

paper

The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases

arXiv:1905.03751 · doi:10.1016/j.aop.2019.167913

Abstract

Momentum-conserving quasiparticle collisions in two-dimensional Fermi gases give rise to a large family of exceptionally long-lived excitation modes. The lifetimes of these modes exceed by a factor $(T_{F} / T)^{2} ≫ 1$ the conventional Landau Fermi-liquid lifetimes $τ \sim T_{F} / T^{2}$ . The long-lived modes have a distinct angular structure, taking the form of $cos m θ$ and $sin m θ$ with odd $m$ values for a circular Fermi surface, with relaxation rate dependence on $m$ of the form $m^{4} lo g m$ , valid at not-too-large $m$ . In contrast, the even- $m$ harmonics feature conventional lifetimes with a weak $m$ dependence. The long-time dynamics, governed by the long-lived modes, takes the form of angular (super)diffusion over the Fermi surface. Altogether, this leads to unusual long-time memory effects, defining an intriguing transport regime that lies between the conventional ballistic and hydrodynamic regimes.

arXiv comment29 pgs, 6 fgs

The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases

Abstract

References in corpus (5)

Cited by in corpus (45)