Non-equilibrium effects on electron-phonon coupling constant in metals

Abstract

Understanding of the energy exchange between electrons and phonons in metals is important for micro- and nano-manufacturing and system design. The electron-phonon (e-ph) coupling constant is to describe such exchange strength, yet its variation remains still unclear at micro- and nanoscale where the non-equilibrium effects are significant. In this work, an e-ph coupling model is proposed by transforming the full scattering terms into relaxation time approximation forms in the coupled electron and phonon Boltzmann transport equations. Consequently, the non-equilibrium effects are included in the calculation of e-ph coupling constant. The coupling model is verified by modeling the ultrafast dynamics in femtosecond pump-probe experiments on metal surface, which shows consistent results with the full integral treatment of scattering terms. The e-ph coupling constant is strongly reduced due to both the temporal non-equilibrium between different phonon branches and the spatial non-equilibrium of electrons in confined space. The present work will promote not only a fundamental understanding of the e-ph coupling constant but also the theoretical description of coupled electron and phonon transport at micro- and nanoscale.

References in corpus (10)

• Efficient simulation of multidimensional phonon transport using energy-based variance-reduced Monte Carlo formulations
• A comprehensive first-principles analysis of phonon thermal conductivity and electron-phonon coupling in different metals
• Electron-phonon coupling and energy flow in a simple metal beyond the two-temperature approximation
• Electron relaxation in metals: Theory and exact analytical solutions
• Theory of Out-of-Equilibrium Ultrafast Relaxation Dynamics in Metals
• Thermalization in simple metals: The role of electron-phonon and phonon-phonon scatterings
• Theory of the electron relaxation in metals excited by an ultrashort optical pump
• Tracking the time-evolution of the electron distribution function in Copper by femtosecond broadband optical spectroscopy
• Coupled transport of phonons and carriers in semiconductors: A case study of n-doped GaAs
• Nonequilibrium phonon dynamics beyond the quasiequilibrium approach

Cited by in corpus (3)

• Ultrafast dynamics of electrons and phonons: from the two-temperature model to the time-dependent Boltzmann equation
• Energy relaxation and electron-phonon coupling in laser-excited metals
• Energy flow during relaxation in an electron-phonon system with multiple modes: A nonequilibrium Green's function study