Long lifetimes of ultra-hot particles in interacting Fermi systems

TL;DR

This paper investigates how hot electrons in various interacting Fermi systems exhibit non-monotonic relaxation rates, revealing that ultra-hot electrons can regain coherence at high energies, supported by theoretical analysis and experimental observations.

Contribution

It provides a comprehensive theoretical analysis of relaxation rates across different Fermi systems, explaining the non-monotonic energy dependence and coherence revival of ultra-hot electrons.

Findings

Relaxation rate is non-monotonic with energy.

Ultra-hot electrons regain coherence at high energies.

Theoretical results align with recent experimental data.

Abstract

The energy dependence of the relaxation rate of hot electrons due to interaction with the Fermi sea is studied. We consider 2D and 3D systems, quasi-1D quantum wires with multiple transverse bands, as well as single-channel 1D wires. Our analysis includes both spinful and spin-polarized setups, with short-range and Coulomb interactions. We show that, quite generally, the relaxation rate is a non-monotonic function of the electron energy and decays as a power-law at high energies. In other words, ultra-hot electrons regain their coherence with increasing energy. Such a behavior was observed in a recent experiment on multi-band quantum wires, J. Reiner et al, Phys. Rev. X {\bf 7}, 021016 (2017).