Boltzmann-Langevin theory of Coulomb drag

Understand

We develop a Boltzmann-Langevin description of Coulomb drag effect in clean double-layer systems with large interlayer separation $d$ as compared to the average interelectron distance $\lambda_F$.

• Coulomb drag arises from density fluctuations with spatial scales of order $d$.
• At low temperatures, their characteristic frequencies exceed the intralayer equilibration rate of the electron liquid, and Coulomb drag may be treated in the collisionless approximation.
• As temperature is raised, the electron mean free path becomes short due to electron-electron scattering.