Exciton magnetotransport in two-dimensional systems: Weak-localization effects

TL;DR

This paper investigates how magnetic fields influence exciton transport in 2D disordered systems, revealing classical suppression and quantum-enhanced mobility effects, with potential implications for excitonic device performance.

Contribution

It introduces a theoretical analysis of exciton magnetotransport, highlighting the nonmonotonic behavior of diffusion constant due to weak localization effects in 2D systems.

Findings

Magnetic field suppresses classical exciton transport.

Quantum corrections cause nonmonotonic diffusion behavior.

Positive magnetodiffusion effect occurs at weak magnetic fields.

Abstract

We consider the effect of a magnetic field $B$ on the transport of neutral composite particles, excitons, in weakly disordered 2D systems. In the case of classical transport, when the interference of different paths is neglected, the magnetic field suppresses exciton transport, and the static diffusion constant $D(B)$ monotonically drops with $B$. When quantum-mechanical corrections due to weak localization are taken into account, $D(B)$ becomes a nonmonotonic function of $B$. In weak magnetic fields, where the magnetic length is much larger than the exciton Bohr radius, $l_B >> a_B$, a positive magnetodiffusion effect is predicted, i.e., the exciton mobility should increase with $B$.