Energy relaxation dynamics in a nodal-line semimetal

TL;DR

This paper investigates how electrons in nodal-line semimetals relax their energy after excitation, revealing unique exponential and linear relaxation behaviors influenced by phonon interactions and initial conditions.

Contribution

It provides a detailed analysis of temperature relaxation dynamics in nodal-line semimetals, highlighting the effects of phonons and initial excitation conditions on relaxation forms and rates.

Findings

Temperature relaxation due to acoustic phonons is exponential and depends on initial conditions.

Relaxation rates vary with electron density as n^{1/2} for acoustic phonons.

Optical phonon relaxation rates scale as n^{-1/2} or n, depending on conditions.

Abstract

We study the temperature relaxation dynamics of nodal-line semimetals after a sudden excitation in the presence of acoustic and optical phonon modes. We find that the nodal line constrains the electron momenta in scattering processes and, as a result, the temperature relaxation due to acoustic phonons is exponential as a function of time. However, depending on initial conditions, other functional forms are possible. In typical pump-probe experiments, the temperature relaxation is linear due to acoustic phonons with rates that vary as $\sim n^{1/2}$ with density. The temperature relaxation due to optical phonons is also linear with rates $\sim n^{-1/2}$ or $\sim n$.