A simple model for longitudinal electron transport during and after laser excitation: Emergence of electron resistive transport

TL;DR

This paper presents a new resistive transport model explaining electron velocities during laser excitation, highlighting magnetic field effects and unifying different transport regimes, with implications for ultrafast electron dynamics.

Contribution

It introduces a resistive transport theory that accounts for electron deacceleration post-laser excitation, advancing understanding of electron transport phenomena.

Findings

Magnetic field steers electrons along light propagation.

The free-electron model underestimates experimental velocities.

Resistive transport explains the observed distance-time curve.

Abstract

Laser-driven electron transport across a sample has garnered enormous attentions over several decades, as it provides a much faster way to control electron dynamics. Light is an electromagnetic wave, so how and why an electron can acquire a longitudinal velocity remains unanswered. Here we show that it is the magnetic field that steers the electron to the light propagation direction. But, quantitatively, our free-electron model is still unable to reproduce the experimental velocities. Going beyond the free electron mode and assuming the system absorbs all the photon energy, the theoretical velocity matches the experimental observation. We introduce a concept of the resistive transport, where electrons deaccelerate under a constant resistance after laser excitation. This theory finally explains why the experimental distance-versus-time forms a down-concave curve, and unifies ballistic and superdiffusive transports into a single resistive transport. We expect that our finding will motivate further investigations.