Temperature-driven transient charge and heat currents in nanoscale conductors

TL;DR

This paper investigates the short-time dynamics of heat and charge currents in nanoscale conductors under a temperature gradient, revealing transient behaviors, wavefront velocities, and quantum interference effects.

Contribution

It introduces a method using Luttinger's thermomechanical potential to analyze transient thermal and electrical responses in nanoscale systems, highlighting novel phenomena.

Findings

Charge current initially opposes steady-state direction

Wavefront velocities are constant and density-independent

Quantum interference causes temperature and potential oscillations

Abstract

We analyze the short-time behavior of the heat and charge currents through nanoscale conductors exposed to a temperature gradient. To this end, we employ Luttinger's thermomechanical potential to simulate a sudden change of temperature at one end of the conductor. We find that the direction of the charge current through an impurity is initially opposite to the direction of the charge current in the steady-state limit. Furthermore, we investigate the transient propagation of energy and particle density driven by a temperature variation through a conducting nanowire. Interestingly, we find that the velocity of the wavefronts of, both, the particle and the energy wave have the same constant value, insensitive to changes in the average electronic density. In the steady-state regime, we find that, at low temperatures, the local temperature and potential, as measured by a floating probe lead, exhibit characteristic oscillations due to quantum interference, with a periodicity that corresponds to half the Fermi wavelength of the electrons.